Speeding headfirst down the elevator shaft, Dib reached the bottom in no time and swooped forward to dart through the closed doors and end up back in the lobby. He pulled up short, looking around quickly. There were agents running all over the tiled floor, exchanging hasty words between them and questioning each other for news on the demon situation before dashing off again. The sleeping receptionist at the desk was gone—she'd probably been carried off to an observation room by someone.

No sign of Gaz. Dark-clothed agents of all shapes and sizes passed right through Dib on their hectic trips across the room, but his sister was nowhere to be seen.

"Fire! There's a fire upstairs!" Dib shouted at them uselessly, rising up in the air so he was floating above the chaos. They couldn't hear him.

After a couple minutes of circling the room in search of Gaz but still not finding her, Dib turned to head back to the elevator. Maybe he could still do something to prevent whatever Bill was planning.

He caught a glimpse of purple out of the corner of his eye and whipped back around to see a small figure walking leisurely across the floor. "Gaz!"

Bill hadn't been lying after all. Gaz was here! …Somehow.

Gaz didn't notice his shout and kept walking, clutching something in one hand. It was the dirty moose toy that Dib had stolen from GIR and abandoned outside the building. Why she was carrying that, Dib didn't know, but he dived down to wrap his hand around it and brought himself forward to face his sister directly. "Gaz!"

She released the moose, squinting up at the sound of his disembodied voice. "Dib?"

"Gaz, it's me!" Dib floated upward a bit and clutched the doll to his chest. "I can't believe you're here!"

Finally, someone to help him! He had an ally at last! With Gaz by his side, taking down Bill would be no problem. He'd been waiting all day for—wait. Dib faltered and his voice took on a more frenzied edge. "Wait, no, Gaz, you've gotta get out of here! This place is on fire!"

"You're… possessing that gross moose toy." Gaz raised an eyebrow at the doll and ignored Dib's other comments. "I should've guessed. I saw it outside and figured you needed it because that's the kind of dumb thing that would happen to you. It's a little… much, though."

"Uhh… well, no, I'm not possessing it, I'm just holding it." Dib bobbed up and down in the air. "Listen, an evil mind demon took control of my body and is planning on destroying this place!"

While he talked, one of the Swollen Eyeball agents running by stopped to give Gaz a bewildered look. "Little girl, how'd you get in here? You're not supposed to be here!"

"Maybe you should make this place harder to break into then," Gaz said, cracking open one eye to glare at him. The man left in a hurry.

Gaz crossed her arms and turned back to Dib. "A mind demon taking over your body, destroying this place, yeah. I heard about that."

Taken aback, Dib drifted down closer. "Really? You did? From who? And how did you get in here?"

"Staff entrance," Gaz replied with a shrug. "And I heard about it from some kid in Oregon."

Dib had no idea how anyone from Oregon would know about their current situation, or how they had been able to contact Gaz, but that hardly mattered right now. "Okay, look, we have to find Bill and get him out of my body before he burns this entire place to the ground! I'm just glad he hasn't found the self-destruct buttons—"

At that moment, the blaring of emergency alarms filled the air and red lights on the ceiling started flashing. Dib's mouth dropped open in horror. The agents around the room skidded to a stop, huddling together and staring up at the lights.

Gaz, however, looked unimpressed and just glanced up at the ceiling. "I take it that means he found the self-destruct buttons."

Dib sucked in his lower lip with a sharp gasp. He buried his head in his hands, inadvertently making that stupid toy moose squeak. "WHY did I make that DEAL?"

There was a long, low bloop that could just faintly be heard over the alarms.

"Hey again!" an all-too familiar voice said over the speakers hidden in the ceiling. That thieving triangle demon. He'd been climbing the elevator shaft a minute ago—where was he now?

Bill continued, "So, you've probably noticed that there are some alarms going off and a supernatural fire may or may not have broken out on a couple of floors! Don't worry, this is all completely intentional! None of you will probably make it out of here alive!"

"Evacuate! Evacuate!" someone cried, and all the agents ran for the elevators.

"Gaz, come on, Bill's using the PA system!" Dib said. "He's obviously not at the desk down here and Darkbootie's office on the ninth floor is probably still swarming with agents, so he must be up on the ground floor!" Still gripping the moose, he dove toward the stairwell door and hoped that Gaz was following right behind him. "Head for the stairs!"

Gaz pushed past the few agents blocking her way to the door and opened it, allowing Dib to fly through with the moose. She let the door swing closed behind them and started up the concrete stairs.

Bill's voice continued. It was louder in the stairwell, since there were no alarms, and Dib itched to cover his ears and block it out. "I have to say, you people are pretty amusing! It's hard to have this much fun anywhere else but Gravity Falls!"

"Come on, we need to hurry," Dib said. He raced up the stairs and could hear the echoing footsteps of Gaz running after him. She was following, but she didn't say a word.

They made it up a couple of floors before Dib heard the screaming.

"Do you hear that?" he said. The yells came from behind the door they'd reached.

"Sounds like Zim," Gaz said.

She was right—only one person screamed like that. Dib hovered in front of the door, looking down at Gaz. "Quick, open the door!"

Gaz pushed it open and gasped as white fire surged outward, running halfway up the next flight of stairs to avoid it. Dib looked to make sure she was okay before flying right through. This was the seventh floor—the one that Bill had originally set on fire. Dib reeled backward at the sight of the burning hallway, alight with the white-hot supernatural fire that had come from the lighter on Darkbootie's desk.

Sprinklers on the ceiling had gone off, but they delivered just a drizzle of water rather than the downpour that would be needed to douse the fire. Zim, wearing his wig and contacts, was huddled at the very far end of the hall in a tiny corner that was so far untouched by the flames. He wouldn't be safe there for long, though, which he seemed to know judging by the way he was screaming and whimpering with his arms wrapped around his knees.

Dib skimmed over the fire—he could feel the intense heat on his belly even in his current incorporeal state—and flew down in front of the alien.

"Zim, come on!" he yelled. It was hard to make himself heard over the roaring fire.

"Dib?" Zim lifted his head, looking dazed and disoriented. "I thought you were helping me… find GIR! You left me behind! You- you putrid, loathsome—Where are you?"

"Zim, you idiot, that wasn't me! And we need to get out of here!" Dib snapped. "Get up and go to the exit!"

"And why should I listen to you?"

"Because you're surrounded by fire!"

The alien hissed in a breath and climbed to his feet, pressing his back against the wall with all his fingers splayed out. Dib could almost see his heart (or organ equivalent to a heart) pounding frantically in his chest, and had the strange thought that he might enjoy the alien's terror on any other day. Or should enjoy it. But right now, Zim's palpable fear only succeeded in heightening Dib's own panic.

Zim stumbled forward. He seemed to be on the verge of collapse, veering away from a tongue of flame that snapped out at him and crashing into the opposite wall. Dib grit his teeth and thrust out the toy moose toward him. It was starting to melt in the heat.

"Here, hold onto this!" he said. "I'll guide you out of here, okay?"

Zim blinked smoke out of his eyes and swatted the doll away with a grimy, gloved hand. "Zim needs no help from no moose! I don't fear fire! Fire's afraid of me!"

He tripped and fell face forward on the ground. The white fire swirled around his body, hiding it from view.

"Zim!" Dib yelled, eyes wide. He hovered over the fire, thoughts racing. They needed to get out, Gaz was in danger… Leave Zim behind? Leave him behind…

He half turned to go back to the stairwell with Gaz and jerked in surprise when a gloved hand erupted from the midst of the fire, flailed, and grabbed onto the moose toy. After a second of hesitation, he hauled it toward the clearest path leading out of the hall.

Zim, holding onto the toy in a death grip, crawled out of the fire, gasping. His uniform was scorched in places, his wig was singed and askew, and overall he didn't look all that great, but he was still very much alive. Maybe Irkens were more fire-proof than humans.

He was coughing, shielding his face with his arms to block the smoke billowing in the air as best he could. Part of the ceiling crumbled down next to them and he screeched, leaping backwards and dragging Dib several feet. After a moment he forced himself to continue down the hall. When the doorway was in sight he locked his gaze on it and let go of the moose, the electronic spider-like legs unfolding from his PAK and levering him up into the air. He skittered over the fire and through the door.

Supernatural fire crawled out of the room and into the stairwell, licking at the concrete stairs and causing bits of them to crumble away. Gaz was standing several steps up with her lips tightened and her face drawn in a glare. Zim scaled the steps on his spider legs and Dib flew up to join them.

"We've gotta get to the ground floor!" he urged.

"We would've gotten there quicker if we hadn't stopped for this thing." Gaz shifted her gaze up to Zim. "He's just going to slow us down, you know. I thought you hated him."

Dib was about to protest that he'd almost left Zim behind, but decided against it. There was no time. "Whatever! We need to go."

"I'm not going anywhere until I find GIR!" Zim said. He had regained his composure rapidly and hung in the air with the metallic legs coiled around him, eyes narrowed.

Was no one concerned about the fire raging just below them?

"Zim, your stupid robot is fine!" Dib said. "He's at your house watching TV! If you just called him you'd know that! Now c'mon!"

He floated over Zim and started up the stairwell once more but was stopped once more by the bloop of the PA system over the speakers.

"You know, I was thinking!" Bill Cipher's voice said, sounding cheerful. "You like songs? I've got a show tune in mind that goes out to anyone who's having kind of a rough day today! That is, everyone! Haha, don't worry though, pretty soon this'll all be over! And then after that everything'll go better for you, am I right? I'm right. Here goes!"

Gaz skirted around Zim and arrived next to Dib, scowling up at the ceiling. "Tell me he isn't really going to—"

To Dib's astonishment, the demon started to sing.

"Theeeeee sun'll come out, tomorrow!"

His sister's face darkened. "I hate the universe and everything in it."

"Bet your bottom dollar that tomorrow, there'll be sun…"

"Just ignore it! Keep going!" Dib started moving again, leading the way up the stairs.

It was a long distance from here up to the top floor. Gaz and Zim were still following him, and fortunately Zim offered up no further protests. That was probably because his breaths came in rasping pants as if he were overworking himself, even just walking on his spider legs. The smoke from that fire couldn't have done his lungs (or whatever he had in place of lungs) any good.

"Juuuuuust thinkin' about tomorrow…"

The sounds of the song and their pounding footsteps bounced off the walls and made the space feel even smaller than it really was. The air passing through Dib's ghostly form seemed hot, dry, and static, making him feel like he was in an area where lightning had just struck. Every hall they passed seemed to be wreathed in flames—the thin cracks around the door frames glowed white.

"Clears away the cobwebs and the sorrow, 'til there's NONE!"

Zim jumped at the emphasis on the last syllable.

In front of them, the door leading to the next hallway blew outward from its hinges and smacked the wall on the other side, white flames blasting through the empty space. Gaz drew back, wide-eyed with her arm thrown up to block her face. Zim faltered for a moment but then ran through.

"When I'm stuck with a day that's gray, and lonely… I just stick out my chin, and grin, and saaaaaaaay…. ohhhh…"

"Gaz! Are you okay?" Dib called, fanning at the fire with his hands but of course having no effect on it.

"I'm fine." Gaz edged around the flames and met up with them on the other side. "Let's go."

Bill's voice continued. "Sing it with me! The sun'll come out, tomorrow!"

Gaz growled. "When we find this guy, I'm going to pull his intestines out through his nose."

Dib pretended he hadn't heard that. Hopefully she'd remember that was his body before she attempted any severe damage to his internal organs.

"Soooo you gotta hang on 'til tomorrow, come what maaaaaay! Tomorrow, tomorrow, I love ya, tomorrow! You're always a day away!"

They had reached the top.

Dib, Zim, and Gaz burst out onto the ground floor, only to find the elevator hallway completely deserted. Up here red lights still flashed and the emergency alarm was still going off, the volume of it almost but not quite drowning out Bill's song.

"When your world falls apart, it's dark, and you're frantic… I'll just stick out my chin, and grin, and saaaaaaaay, ohhhh…"

"Where to now?" Gaz demanded.

"He's got to be up here!" Dib said. But where? "There's a little conference room somewhere up here, I know that. That's probably our best bet on where to find him. Follow me!"

"The sun won't come out, tomorrow! Sorry pal, you won't be here for tomorrow! That's just the waaaaaaaay!"

They raced through the hall, turning corners as he directed and glancing into each room as they flashed by. Where was Bill?!

"Tomorrow! Tomorrow! I love ya, tomorrow! For some you're an eternity away!"

This floor wasn't very large. There were only two more rooms to check.

Bill chuckled over the PA system. "Heh, I probably need to fix up the wording there a little, but here comes the big finish! TooooooMORROW! Tomorrow! I love ya, tomorrow!"

One more…

"For some, you're just toooooooo…"

"Far…."

"Awaaaaaaaaayyyyyyyyyy!"

Gaz flung open the door to the last room.

About ten feet away from them, at the end of a long table, sat Bill. He was twisting back and forth in a swivel chair and finishing his song into a headset he was wearing. A slow smile spread across his face at the sight of them and he stilled the chair, reaching up and turning off his headset with a click.

"Good timing! Enjoy the song?" he said. "I spiced up the lyrics a little for that last part!"

There was a satchel sitting on the table, which he pushed to the side. It was the bag he'd filled up and taken from the secret room of Irken equipment and other top secret paranormal artifacts.

He shifted his eyes to Zim, resting his elbow on the table and propping his head on it. "How ya doin' there, Bug-Eyes? Still convinced your robot's locked up here somewhere? Those fake memories were a snap to assimilate into your mind. You're completely loyal to those ridiculous leaders of yours and you're paranoid and you're stupid. I love it!"

"You dare insult the Almighty Tallest, Dib-worm?!" Zim spat, slamming his hands down on the table. "They'll bring the Armada and incinerate this filthy planet to the core!"

Bill grinned and templed his fingers on the tabletop. "That sounds like a lot of fun to watch! But I have my own plans for this place!"

"You can't have plans for this planet! I have plans for this planet! No one takes my conquest from me!"

"Yeah, yeah, I get the point, knock it off." Bill waved his hand.

Gaz came forward and leveled her eyes on him, looking him up and down. "So you really are a demon, huh? I guess that explains why you were acting so dumb this morning."

"Demon! Yep! Pretty much sums it up!" Bill reached up to his head and tipped an imaginary hat. "Bill Cipher's the name! And I know you three well enough by now—Foureyes, Greenie, and the sister."

"Great. I don't care." Gaz advanced toward him, glaring. "Get out of Dib's body. Now. There's enough paranormal junk around here already."

"Get out? So soon? But I just discovered spinny chairs!" Bill pushed off against the table and spun his chair so fast he was just a blur. "Hahahahahaha! Who'd want to give this up? Look, no hands!"

Gaz shot out her hand and caught the back of the chair, bringing it to an abrupt stop. Bill flew out of it and toppled to the ground. Gaz let go of the chair and looked down at him with a stormy expression. "Get out. By the way, you almost got the 'ominous villain in swivel chair' thing right, but then you ruined it. And you don't even have a cat to stroke."

The demon got back to his feet, leaning against the table on one hand. "Oh, that's hilarious! Am I really supposed to believe that all of a sudden you're concerned for your sibling? That doesn't seem very characteristic of you, Squinty! When did you drop that whole apathetic thing you had going on? Don't you have some violent video games to play or something?" He snapped his fingers. "And besides, your weird brother and I made a perfectly valid deal!"

"There was nothing valid about it! You tricked me!" Dib shouted, rushing across the room to glare into Bill's face.

Bill didn't move and simply bared his teeth at him. "Oh, hey! Didn't see you there! Haha, I'm kidding! I see everything." He gave the moose doll Dib was holding a flick with his thumb and forefinger. "Nice moosey dog toy you've got there! What's with the people in this city and moose, anyway? It's like an obsession! You're almost as bad as Gravity Falls is with its owls!"

Dib backed off to hover next to Gaz for a moment. He leaned down, speaking into her ear in a lowered voice. "He won't give up my body easily! You'll have to fight him, Gaz! Go for the eyes! …No, wait, then you'll end up hurting my eyes. Is there any way you can defeat him without severely injuring me? Maybe you could trap him somewhere and—"

"Hey, Dib?" Gaz said, one eyebrow raised.

"Yeah?"

"Shut up."

Dib closed his mouth, frowning.

"Yeah, listen to your pizza-loving sister!" Bill said, looking at them intently. "Anyway, Foureyes, I wanted to show you something! Guess who entered the code to complete the self-destruct sequence?" He got up, brushing Gaz aside and walking to the far wall. There was a little metal fuse box bolted there, with a keypad inside and the door hanging open. Bill snapped it closed. "Three guesses! It was 'you'!" He pointed at himself. "Looks like you're gonna have your name stamped on all the paperwork explaining why this place went up in flames!"

He pulled the little lighter out of his pocket. "I could set this floor on fire, too, if you wanted! See how that goes! I mean, eventually the place will either explode or the fire downstairs will make its way up here anyway, but maybe you'd rather get it all over with quickly!"

Bill clicked open the lighter and a little white flame flickered.

"Nyah!" Dib cried, reaching down and making to grip his sister's shoulder. "Gaz, you can't let him! He's the only one who can open the front door and get out of the building! The hand-scanner won't work for you or Zim!"

Gaz stood stock still. She didn't even look at Dib hovering over her shoulder. Her eyes were only for Bill. "No. You. Don't."

The white lights on the ceiling blew out one by one in a wide ring around Gaz. In a second the entire floor was illuminated only by the flashing red emergency lights, leaving the place in complete darkness every other second as the lights went on and off. The alarm was still shrieking at full volume.

Bill, highlighted in red every second or so by the light, glanced around with a confused expression. Gaz stomped up to him, drew back her fist, and socked him right in the face.

Dib cringed.

Bill cried out and fell backwards, slamming into the table and falling to the ground. He pushed himself back up into a sitting position, sputtering. His nose started bleeding again and it dribbled down onto his already-stained clothes.

"Aw, come on, you knocked off my glasses!" Bill said, squinting at Gaz and wiping at his bleeding nose. Blood smeared across the back of his hand. He felt around on the ground and, unable to locate the glasses immediately, stood back up.

"You're lucky I only punched you," Gaz said. "Maybe you'd rather I tear both your arms off."

"What? Gaz, can we talk about this…?" Dib asked, staring at his body in alarm.

"Hah! It'll take a lot more than losing a pair of fleshy noodle arms to make me—!" Bill took a step forward and cut himself off at the loud crunch under his feet. "Oh, whoops!"

He lifted his foot and picked up Dib's glasses from the floor. One of the lenses was cracked through and the frames were bent. Dib scowled. It was like Bill was determined to break everything he owned.

"Okay, I'll admit I didn't even do that on purpose!" Bill said, as if he'd read Dib's mind. Which he probably had. He sat the broken glasses back on his face and gave a manic grin. "You have to admit this is a good look for you, though, scythe-head! Very fitting!"

Gaz threw another punch while the demon's attention was focused on Dib, but this time Bill caught her fist before it landed. Gaz's eyes flashed and Bill looked around to smile at her, tilting his head to the side without blinking once. Reflections of the red emergency lights glinted in his eyes.

"Sorry, Skully!" he said. "There's no more time for that!" He pushed Gaz backwards and let go of her hand. She stumbled a bit, but then lunged forward and clapped both her hands over his ears as hard as she could. He gasped and pulled away, grabbing the sides of his head and squeezing his eyes shut as he tried to shake off his disorientation. "Whoa! Ow! What was that?"

Dib swooped down, swung out the moose toy, and knocked the glasses off his body's face and onto the floor.

"Ha!" Zim ran forward, his spider legs retracting back into his PAK, and picked up the glasses. He tightened his fist around them and brandished them at Bill. "I have your glasses, Dib!"

"Zim, for the last time, that's not me!" Dib shouted.

Bill let go of his head, took a step forward, and crashed into the chair he'd been sitting in earlier.

"Oh, come on, seriously, what is the point of these eyes?" he demanded, shoving the chair out of the way and whipping his head back and forth to try to locate Zim. "Can you even do simple echolocation? No, you can't! Because humans are blind!"

Gaz climbed over the table and went to the fuse box, flipping it back open and scrutinizing the buttons inside with narrowed eyes. She growled. "There's no way to turn this thing off."

"Huh? Are you sure? There's gotta be something!" Dib rushed over to bob up and down in the air next to her, staring at the box. "Who would make a self-destruct sequence that can't be averted at all?!"

"Don't ask me. You're the one who's involved with these people."

"Rrgh, move out of the way!" Zim vaulted over the table and pushed Gaz to the side, peering at the little box himself.

Gaz grunted and clenched her fists. "If one more person pushes me, this place will go down in flames."

"Zim, you're supposed to be distracting Bill!" Dib said.

The demon, who'd picked up his satchel and wandered to the other side of the table, turned his head in their direction with his eyes narrowed. He wasn't smiling anymore. "You can blind me, you glasses-wearing freak, but you can't distract me. I know everything that all three of you are thinking! I'm the master of the mind, remember?"

Zim looked away from the keypad and studied Bill for a moment. At last his eyes widened in shock, then took on an accusatory expression. "Hey! You are not the Dib!"

"Wow, that took you long enough!" Bill said.

The demon didn't get to continue. Zim's spider legs unfolded again, arced around his body, and shot a laser at Bill, blasting him back several feet. He skidded all the way across the room, hit the wall near the door, and slumped to the floor unmoving.

"Nyah!" Dib cried in horror, hands flying to his mouth. "How many times am I going to have to watch myself die today, huh? Huh?"

"Nice shot," Gaz said.

Zim went back to work on the keypad, peering closely at it. He pulled away with a stricken expression on his face and snarled. "This looks like Irken technology! Your parachutey eyeball society reverse-engineered the Megadoomer and stole the self-destruct sequence!"

"If it's Irken, can't you shut it off?" Dib asked, floating by Zim's head to look over his shoulder.

"Of course I can!" Zim said. He reached into the box and fiddled with some wires, then jerked back with a yelp. He'd shocked himself.

"Ahahahaha."

Laughter came from the front of the room. Dib, Gaz, and Zim looked over to see Bill struggling to his feet with one hand braced against the wall, the other clutching his satchel.

"Listen, enough's enough! You have to stop this!" Dib pleaded, flying a little closer to him. "Just stop! Stop the fire, stop the self-destruct, and go back where you came from! Our contract is through! I banish you back to the black netherworld from whence ye came!"

"Ahahaha!" The demon was still snickering. "Oh, but—" he panted, "—dear little scythe-head, we had an agreement! I'd—give your little green friend some fake memories, and you'd help me destroy—an organization! If I'm not mistaken, this place isn't entirely destroyed yet!"

"Fake memories?" Zim repeated.

"That's stupid! The memory didn't even work!" Dib said, gesturing at Zim. "He's still in disguise! Which means you didn't do your part of the bargain right!"

"Fake memories?" Zim rounded on the floating moose, apparently finally figuring out that Dib was the one holding it. "What fake memories? What did you tamper with?"

"You three should be glad I didn't just—ask for a puppet to control, with no determinate time limit!" Bill said, smiling. "Who knows what might've happened? Now if you would—just give me back those pain-in-the-vertex glasses, I'll be outta here!"

Zim threw the glasses on the ground and crushed them under his boot, leaving them mangled beyond repair.

Dib dropped his arms. Great.

Recognizing the crunch of glass, Bill frowned, but then shrugged. "All right, sure, I can live with that! Catch me if you can!" He located the door handle and pushed his way back out into the hall, still wearing the headset and carrying his satchel and lighter.

"He's going to try to leave the building," Gaz said.

Dib turned back to the fusebox. "Zim, stay here and do whatever you can to deactivate the self-destruct! Gaz, c'mon, we've got to go get my body back!"

"When this is all over, Dib-human, I'm going to release ten thousand mutant biting things into your room," Zim growled, examining the fusebox once again.

"Whatever, Zim. Come on!" Dib led Gaz out into the hall, scanning the area for Bill. The demon couldn't have gotten too far. He had to be sick and worn out from all the injuries he'd inflicted on Dib's body. Right? And he was pretty much blind without the glasses. But if he managed to get out, they'd all be stuck in a burning building unless another agent arrived and opened the door for them…

They made their way back to the entrance to the headquarters and found Bill standing by the door, feeling around the frame. As they approached his fingers bumped the edge of the hand scanner and he smiled. "Aha! Found it!" He reached for it, palm outstretched.

The scanner burst into bright orange flames just before he touched it.

"What the—?" He snatched his hand back, looking down at the lighter he was holding in a split second of confusion.

The rest happened so fast that Dib almost missed it. The alarm that had been shrieking the entire time went mute and the red emergency lights shut off, leaving the faint golden glow to Bill's—Dib's—eyes as the only light sources. Gaz was suddenly next to Bill and she tackled him to the ground. Her eyes were flashing again—literally this time, and Dib saw the world crumble away and fire erupt around the room. But it wasn't the white fire that was taking over the lower floors—it looked like normal fire, though it did have a strange and unearthly feeling about it. Dib rubbed his eyes and blinked. The fire and the ruins of the room flickered in and out of existence. It was just an illusion.

Bill was crumpled up on the floor, his hands and knees curling into his body. The headset had fallen onto the floor and his lighter was nowhere to be seen, though he still had his satchel tucked under one arm. He looked up at them, one of his eyes rimmed with an ugly purplish black color and swollen nearly closed. Blood dribbled from the corner of his mouth—he must have seen the fire, too, because he looked around the room with his eyes as wide as they would go. His facial expression when he looked up at Gaz was almost impressed, and maybe, for an instant, even a little fearful.

"What are you?" he said.

"I'm sick and tired of having to come rescue my stupid brother again." Gaz lifted up Bill by the edges of Dib's trenchcoat and dragged him to the edge of the hall, looking down into the abyss where the floor had been just moments ago. "Now get out."

She heaved him forward, dropping him over the edge of the chasm as he screamed and flailed. Dizziness crashed down over Dib and the world seemed to tilt dangerously to the side, making him feel nauseated. There was a snapping sensation, like someone had drawn back a rubber band as far as it would go and then released it, and the entire illusion of the fire shattered.

The regular lights slowly came on again. Across the room, right where Gaz had dropped it, Dib's body was limp and his eyes were closed. The emergency lights and the alarm stayed off, causing Dib to wonder if Zim really had succeeded in shutting off the self-destruct sequence. It took him a minute to realize that color had drained out of the world, leaving everything in shades of black and white. He recoiled—Bill Cipher, in his normal triangular form, was floating right next to him with his arms outstretched by his sides and his feet angled downwards.

"Did you know your sister has enough power to expel a demon?" Bill said. "That's funny, if you didn't! Considering paranormal study is supposed to be your area of expertise!" He laughed, tipping his hat. "Anyway, it's been fun, kid—but I think we were just getting started! I wouldn't go anywhere, if I were you! Later!"

He zipped away somewhere, leaving ripples in his wake.

Dib darted down to his body, hardly able to believe it. He touched his hand and everything went black. Feeling suddenly flooded in from everywhere—he was lying on a solid plane, touching the ground for the first time in hours; he could feel the weird satchel clutched under his arm, and shaky breaths rasped in his throat.

Also, everything hurt.

The sensation of pain had been slightly delayed, allowing him a blissful second to enjoy being rooted back in reality before he tensed up and snapped open his eyes with a gasp. The world was just smudges of color. His left eye could barely open and caught nothing but a bit of light. He pushed himself into a crouching position, his arms trembling.

"Gaz?" he said. His voice was a whisper.

Something grabbed the back of his trench coat and hauled him to one side. He twisted around to see that the thing holding him was a blur of familiar black and purple.

"Gaz, wait! Stop!" he cried. "It's me! I'm back!"

"I know that." Gaz dropped him on the ground in a heap. "Don't move."

"What—"

He couldn't see her face, but he could feel her looking down at him. She said, "So Zim made a deal with that stupid demon too, huh?"

Across the room, a laugh rang out. Dib jerked his head up and saw a small pink blob swaying near the ceiling. There was the clinking and clattering of the Zim's weird metal spider legs—he must have been propped up in the air on them, though they were too thin for Dib to see clearly.

"Now this is more like it!" Zim cackled. Dib's breathing hitched. Zim's voice sounded nearly the same as it always did, but he had a nasty feeling that the alien wasn't the one saying those words. With an effort, he raised himself onto his elbows and stared horror-stricken at him.

Clickclickclickclickclick. Zim—or, Bill in Zim's body—skittered over to Dib on the spider legs and lowered himself down to yank the bag out of Dib's arms. Dib shrank back. He could see Zim's face clearly now. The alien was wearing the exact same grin that had been plastered over Dib's face all day (his cheek muscles were burning now), though his eyes were the same blue-gray color he used as his disguise. Maybe the slit pupils indicating possession by Bill didn't work on contacts. Or on alien eyes that didn't have real pupils in the first place. Or maybe only the spirit of the possessed person could see the change in their eyes and hear the wrong voice coming out of their mouth.

"Now, if you'd kindly open the door for me!" Bill said. He glanced over his shoulder. "Hah! Finally gotten with the program there, Buggy? Remember the favor I wanted you to do for me earlier? This'll work!"

He must have been talking to Zim—who, with no vessel to speak through, could only be heard by the demon himself. When had they made a deal?

There was a click, a white glow, and Bill turned back to find a white flame flickering in his face. Gaz had picked up his lighter and stood over Dib. She brandished the little flame as a weapon.

"Really? You're going to keep me away with that?" he said.

Gaz reached up and set his wig on fire. Bill yelped, beating at the flames with gloved hands before snatching the wig off his head and throwing it across the room where it smoldered on the floor.

Dib heaved himself to his feet, bracing his back against the wall. Exhaustion and numbing pain caused his entire body to droop. He couldn't even try to keep track of how many injuries Bill had caused him. He'd have to deal with that later.

"All I need is your handprint!" Bill said, advancing closer to Dib and Gaz. His mouth was bared in his usual wide smile that displayed all his teeth and gums, and the two thin antennae on his bare scalp were skewed in different directions. "Trust me, I can do a lot more damage in this body than I ever could in that one! This thing was made for destruction! All I have to do is—"

Something smacked Bill in the side of the head and fell to the floor. He winced and looked down at it, kicking it away with one spider leg. It was the toy moose. Dib had dropped it when he'd reclaimed his body.

"Taken to throwing things, Greenie?" Bill said.

The moose rose into the air and a voice erupted from it. "Remove yourself from the body of Zim!"

The toy moose flew forward, colliding again and again with Bill's head as Zim's spirit attacked his own body with vehemently. "Get out! Out! Get out!"

Bill swatted him away. "Hah! All three of you, I don't know whether to be impressed or annoyed with your persistence! This really is the best you can do, isn't it! Holding a lighter in my face? Hitting me with a rubber toy? Granted, Skully's got some sort of power over there, but what does that matter? This is great! Also, gotcha!"

He grabbed the moose toy out of the air, turned, and flung it at Gaz, knocking the lighter out of her hand and causing it to skid across the floor. She backed up a couple of steps and ran to retrieve it, leaving the demon-possessed alien alone with Dib.

"Looks like one of us still has to finish his end of our little agreement!" he said, smiling. As Dib watched, Bill reached up to his face with both hands and peeled away the contacts covering Zim's eyes, letting them drift down to the floor. He'd gotten rid of the last of Zim's disguise. "And it isn't me!"

Dib glanced at the doors behind him. "You just want to get out with that bag of yours," he said. "What's in there? You said something about memories—why do you need them?"

"Hey, if memories have been stolen by that stupid gun, there's a chance even I haven't seen them!" Bill replied.

Obviously the memories in that bag were important. And if Bill needed them, under no circumstances should he be allowed to escape with them.

Once again, the toy moose flew out of nowhere and struck Bill in head. He growled and diverted his attention from Dib, looking up at where Zim's spirit must have been floating. "Enough already!" he said. "Look, do you want me to get irritated? I can get irritated! You do not want to see me irritated!"

While he was distracted, Dib dodged around him and stumbled back across the room, searching the muddled environment for any sign of his sister. "Gaz! Don't let Bill get out of here!"

Gaz arrived by his side. "Got the lighter," she said. "Doesn't really do too much against him, though."

"Look at this! Everyone wants to get pelted in the head by a moose toy!" Bill said, attempting to shield his head from the continued onslaught of Zim's moose attacks. "What's with this? You're not really deterring me, you know! This is just ridiculous!"

There was the sound of thundering footsteps in the hall behind them. Seconds later a group of three Swollen Eyeball agents appeared, two of them running forward and grabbing Dib by the arms.

"Got him!" the one on the right said.

Bill grabbed the moose out of the air again and this time tore its head off, dropping both rubber ends on the ground and cutting off Zim's one mode of communication. He burst out laughing. "Yep, you sure got him! Welcome back, trench coat and fedora-wearing secret agent wannabes! How's the fire going?"

All the agents looked so alike to Dib without his glasses that he wasn't able to recognize any of them. "Agent Darkbootie! Is Agent Darkbootie here?" he asked. "I'm back to normal!"

The third agent came forward, looking from Dib to Zim's body. The latter was grinning so widely that even Dib could see his teeth.

"It's the green one," the agent said. It was Darkbootie's voice. "Get the green one!"

One of the agents released Dib and rushed forward, but Bill didn't move. He stood with his arms behind his back like he was waiting for him.

Realization dawned on Dib and he cried out. "Wait! Stay away from him!" he said. "He just wants one of us to open the door so he can get away with that bag!"

The agent skidded to a stop, standing a few feet away from Bill.

"Haha! Oh sure, who knows!" Bill said. "Someone's flailing hand might accidentally hit the extremely precise hand scanner! Maybe you'd all better stand back there and just idle around!" He rose up higher on the spider legs, swinging out frontmost ones so they crashed down on either side of the agent. "But the funny thing is, I'm not leaving until someone opens the door!"

"Why doesn't he just blast it down?" Dib muttered, dazed.

"I'd love to!" Bill replied, looking up. "But the doors leading out of the building are a little more well-reinforced than the door leading to the little secret room that your alien friend broke into! I kinda doubt I'd even dent them!"

The agent tried to run back to the rest of the group but Bill lunged out, grabbing him by the back of the coat and poising the nearest spider leg so the pointed end was resting over the agent's heart.

"Hah, that was easy! I guess they just don't make paranormal investigators like they used to!" Bill said, drawing the captured agent backwards. "Makes things easier for me, I guess! So here's the new deal! This guy here—what's your name? Haha, kidding, I know your name! Agent Shaky-Hands here is going to open the doors for me! Or, heh, y'know, we'll find out how good these cool appendages are at sharply poking things!"

He shifted the point of the spider leg up a little and the agent stiffened, his breath hissing through his teeth.

"Get back!" Agent Darkbootie ordered, drawing Dib, Gaz, and the other agent backwards.

Dib pulled away from him and hobbled forward. "Bill! Let him go!"

"Something wrong, pint-size?" Bill said. He towered over Dib, smiling down at him.

Dib took a deep breath. "I'll open the stupid door for you, you jerk," he said. "Just let him go."

The demon alien paused. "Sure, all right!" he said, releasing the agent and letting him drop to the ground. "I don't care who opens the door! Might as well be you, Dibbers!"

Dib cringed at the seldom-used nickname. The agent he'd freed had landed in a crumpled pile of trench coat on the floor. He whispered "Thanks, I owe you," to Dib, then scuttled back to the others. Dib drew himself up and limped toward the door. He paused. What was he doing? There was nothing keeping him from running—

Something sharp poked him in the back. Craning his neck, he looked over his shoulder and saw that Bill was right behind him, balancing on three spider legs while the fourth prodded Dib right between the shoulder blades.

"Go on!" Bill prompted.

"Call for backup!" Agent Darkbootie ordered one of the other agents.

"Uh, sir, everyone's kind of panicking right now," the agent answered.

Dib tensed and took a few more steps toward the door. He had to figure out a way out of this, play for time or something. But how? Bill could read minds! Maybe he just had to think quickly. Be unpredictable. Like Zim's dumb little robot. What would GIR do?

"Hey, Bill…" Dib turned around, grasping at straws. "Um… do you know any… um… good jokes?"

"Yeah! One time there was a kid who summoned a demon using a two hundred dollar pamphlet from the mall!" Bill said. "And then everyone caught fire and burned to death! Now come on, stalling won't get you anywhere!"

So much for that.

Wait a second… Fire.

That was it. Fire!

"Gaz! The lighter!" Dib said, turning around and pointing up at the nearest ceiling sprinkler he could see. Gaz took the hint at once. She went to the tallest agent, climbed up onto his shoulders despite his surprised protests, and raised the open lighter up to a sprinkler on the ceiling.

The sprinkler she had found came on, dousing her with water. Less than a second later the rest of the sprinklers around the room sputtered on.

Bill backed up and screamed. "What? No! AHH! What's going on? What is this?"

The water hitting his skin sent up small plumes of gray smoke. His PAK legs retracted and he ran from one side of the room to the other, pressing his back up against the wall to try to avoid the water but being largely unsuccessful. Gaz shimmied back down to the ground, nonchalant as ever. When Bill ran across the floor again, she reached out and snatched the satchel out of his hands. Bill skidded to a stop, whirling around.

"All right, I've about had it with you!" he said, jabbing a finger at her.

Gaz looked inside the satchel, raising one eyebrow. "What's this junk?" she asked.

"He said they were memories!" Dib said.

"Memories that belong to TSEN," Agent Darkbootie amended, taking the bag out of Gaz's arms. Bill lunged toward him, but Dib stuck out his leg in front of him. The demon tripped, crashing to the ground.

"Hey Bill, for someone who dug around in his memories, I guess you somehow missed the part where water's like acid to Zim," Dib said.

The demon lay still, the water that still coursed from the ceiling running down his head and PAK and plastering his antennae to his scalp. Darkbootie nodded to the two other agents, who walked forward and took his arms, heaving him back up.

"Oh, I didn't miss that part," he said, looking at them all through hooded eyes. He was trembling involuntarily. Plumes of smoke rose around his body from the burning rain.

"Surrender," Darkbootie said, looking him straight in the eye.

"Yeah, surrender!" one of the other agents—probably the one Bill had threatened—agreed.

The water was still pouring down, wearing on Zim's body more and more. The demon was clenching his fists but for once his face was unreadable. How much of this could he stand? Would he just stand there and let Zim's body burn away?

Surprisingly, Dib's stomach lurched at the thought. Well… maybe it wasn't too surprising, he reasoned. A death like that would be horrific. For anyone.

"Fine!" Bill snapped at last, lifting his head up. "You really think you've won? This organization is nothing! You don't know any real secrets. I could tell you some real secrets! The fire consuming this place isn't even close to what this world has in store. You won't be able to stop it in the end!"

"What exactly are you planning?" Darkbootie demanded.

"Oh, shut up, baldy, I'm not talking to you!" Bill turned and looked directly at Dib, breaking out in a huge grin. "It's been a real pleasure, Frowny-Face! You have way too much in common with Pine Tree, you know that? I imagine we'll meet again some day! In the meantime, enjoy the nightmares! Hahahahaha!"

The alien went limp. The two agents released him, snatching their hands back, and he collapsed in a heap.

A heartbeat later his eyes slid open again and he gasped for breath, clawing at the floor. "Eh… I'm back!" he said. "That horrible thing is gone!" Just then he seemed to notice the agents standing nearby and he shrieked, scrambling backwards. "Stand away! STAND AWAY!"

"Actually, can we replace him with the demon again?" Gaz said.

The sprinklers on the ceiling stopped spraying and only dripped spatters of water down to the ground. The little group stood alone in the middle of the wet tiled floor.

Dib looked at Agent Darkbootie. "…The fire…?" he asked.

The head agent shook his head. "We sent the word to evacuate. We have more exits than the ones up here, but it's impossible to know right now how many have made it out."

"We should get out," one of the agents said. Darkbootie nodded, and everyone hurried toward the main doors. He pressed his hand to the scanner and opened the doors, letting all six of them outside.

Dib had never been more relieved to be out of that building. He walked forward a few paces before sagging to the ground and kneeling down in the grass, convinced that his legs would never move again.

"I guess it's over," Gaz said, coming up next to him.

"It is for Agent Mothman," Darkbootie said. "And you, Mothman's… relative. Mothman, you are suspended from the Network until further notice."

"Huh?" Dib looked up, aghast. "But—that was Bill! All that was Bill, not me!"

Darkbootie had turned to walk away, but now he looked over his shoulder and raised one eyebrow. "Yes, but that demon didn't summon himself. We will be in touch shortly to discuss your status."

And then he was gone.

"Great. I'm going home now," Gaz said a moment later. "You can come with me if you can get there on your own two feet."

Dib had barely any strength left, or so he felt, but he forced himself back to his feet anyway and trailed a few feet behind Gaz as she made her way back home. He let out a long breath. "Well, at least the worst part is over."

"SON!"

A hover screen crashed through the front of TSEN headquarters and zipped over to float in front of Dib. Professor Membrane, framed on the screen, looked livid. "Son, you have a lot of explaining to do about that stolen car!"

Dib sighed.

Everything seemed almost boring once you'd escaped being possessed by a mind demon and managed to avoid burning in a supernatural fire. Of course, maybe that was because Dib had seldom left his room in the past few days after that adventure. He was still recovering. Also, he was grounded.

Not that Professor Membrane was around enough to really enforce the punishment. Dib could probably have left any time he pleased, but he found he enjoyed the change of pace. Relaxing in his room in his pajamas was kind of nice. For now, anyway.

He sat on the edge of his bed, his legs dangling over the side as he tapped his bare ankles together. His eyes were locked on the dark scorch marks still in the carpet. He'd done his best to scrub the area clean, but of course there was only so much he could do to get rid of them. He supposed they'd be there until someone replaced the carpet.

The clock he'd stolen for Bill was long gone. He'd asked Professor Membrane to return that as soon as he'd gotten back home, having no intention to ever look at it again. If the pamphlet he'd used to summon Bill hadn't already been burned, he would have thrown that away too.

He picked up the ice pack sitting next to him on the bedcover and pressed it to his nose, wincing, and scooted back until he had his back up against the wall. A new pair of glasses sat perched on the bridge of his nose. Admittedly it hurt to wear them, but he refused to be without them again.

A hover screen displaying Professor Membrane floated through his doorway.

"Son, I hope you've learned your lesson by now!" he said, flying over to Dib's bed. "Stealing will not lead you to a successful career as a world-renowned scientist! If you're discovered, you'll lose all credibility!"

"Sorry, Dad," Dib said. He felt like he'd said that at least fifty times in the last few days. Membrane had made it perfectly clear that having a son who stole cars wasn't very good for his image.

Membrane nodded. "Well, I'm off to the Scientists' Retreat, so I'm revoking your punishment at least until I return to the city. You're free to leave, but I expect you to be more mindful of other people's belongings!"

Dib nodded, biting down on the inside of his lip. He'd tried over and over to explain about Bill. It hadn't done him any good, which was about what he'd expected.

The screen turned and left the room and soon afterward a phone started ringing downstairs. Dib ignored it, picking up his laptop from the floor with his unoccupied hand and flipping it open. The phone stopped ringing. Good.

"Hey," Gaz said from the doorway, making him look up. She was holding a phone.

Dib lowered the screen of his laptop a little. "Gaz? Since when do you answer the phone?"

"It's for you." She held out the phone for him, not setting foot in his room.

"For me?" Dib put the laptop down next to him on the bed and slid down onto the floor, going over and taking the phone from her. "Who is it?"

"Find out for yourself. I'm done with all of this." Gaz turned and left, heading back downstairs.

Dib stared after her before putting the phone to his ear. "Hello?"

The person on the other end, a kid, sounded excited. "Hi! Oh man, I'm glad you're okay! I was talking to your sister earlier and found out about the demon thing… Bill Cipher? I've had trouble with him too."

Dib brightened up. "You have? Really? Have you had any other paranormal encounters? Who are you?"

"Whoa, okay, slow down!" the kid said. "Yeah, I've had tons of other encounters. My name's Dipper Pines. What's yours?"

A/N: This is officially the end, right in time for the epic new episode tomorrow! Thank you so much to everyone who's read this thing, commented/reviewed, favorited, and even done flipping FAN ART of it. I would never have gotten this far without you!

Thank you especially to BabyCharmander, who was nice enough to provide ideas and beta-read every chapter :)

A little backstory: I had been wanting to do something where Dib summoned Bill for a long time, alternating between writing a short fic of the summoning and attempting to do a comic of it. I never intended to make a longer story out of it simply because I couldn't think of a decent plot, but then Sock Opera aired and the biggest piece fell into place. The "summoning" fic became the first chapter, and the rest of the story sprang from that.

I had a short epilogue written for this story, but I was advised to cut it out and keep the ending the way it is. If I really do get around to writing a sequel someday (a sequel where Dib and Dipper actually meet up), that epilogue will become the prologue to the sequel, or it'll be some sort of transitional material for it. If I don't write the sequel I'll still post the epilogue to dA and/or tumblr as a bonus thing.

Thank you again! I had a lot of fun writing this, and I hope you've enjoyed reading it! If you're up for it, tell me what you thought :)