Note: Pretty sure I'm in danger of the fan fiction police kicking in my door and dragging me away for starting yet another fic. Anyway, here's a Ghost AU. :)

Funny, Sokka thought later, how a life could completely change— or end, whatever—in the blink of an eye.

One moment he was huddled with Katara along with some unfortunate Earth Kingdom villagers, watching Aang get smacked around by a very angry black and white spirit monster.

When the spirit wasn't taking swipes at the Avatar, it was literally punching buildings. At this point, the town didn't have very many left.

Sokka's patience finally broke when Aang was struck so hard, he went flying across a field.

"That's it!" Sokka yelled, rising. "He needs help!"

"Sokka, wait!" Katara called.

Oh, how he wished he listened to her.

But he didn't. He went charging out of the town hall, slipped and accidentally skinned his elbow, then rushed straight over to Aang. Future savior of the world aside, the little airbender had become like a part of the tribe. And you didn't leave your tribe to fight angry spirits alone.

"I don't know what I'm doing," Aang confessed as Sokka helped him stand.

Yeah, that was obvious. "It's okay," Sokka said. "We'll figure this out together."

Then Aang's gaze focused at a point over Sokka's shoulder. His eyes went wide.

Sokka didn't think. He whipped around, throwing his boomerang. "Take that!"

His trusty boomerang hit the oncoming black and white beast… and bounced right off with an actual boinking sound.

The beast roared and swept one hand out to knock Aang to the side again. Then it stood over Sokka. Its jaws parted to show rows of teeth.

Piercing blue light blasted down on Sokka with enough force to knock him to the ground. It was so white hot it felt cold, and so unimaginably loud he felt it in his bones. Sokka might have screamed, but couldn't hear himself.

Then, just as quickly as it started, it ended. Closing its mouth, the black and white monster raised its head—dawn was approaching, brightening the east horizon. Then it turned away and lumbered back to the dark forest.

"Sokka!" Aang cried.

"I'm okay." Shakily, Sokka climbed to his feet… and watched in confusion as Aang ran past him.

"Sokka!" Aang called again. His air staff snapped out and he took to the air, chasing after the monster. "No, bring him back!"

"Aang!" Sokka yelled. "You're going the wrong way. I'm right here!"

The monster disappeared into the forest shadows, gone like it had never been there. Aang flew after it.

Seeing the monster gone, the villagers began to come out of the town hall. Katara pushed past them all and ran forward.

"Sokka! Aang!"

"Aang chased after the monster," Sokka said, frustrated. "I couldn't stop—"

His sister ran straight through him.

There was no sensation at all. Not even a little bit of wind. Sokka clutched his chest, more out of shock than anything, and turned. Katara was still running blindly forward, yelling his name.

"Katara? Wait, Katara! I'm here! I'm right here!"

His longer legs allowed him to catch up. She didn't act like she could see him. Not even when he waved his hand in front of her face.

His sister's lost and scared expression as she stared into the dark forest broke his heart.

One of the villagers approached her cautiously. "Your brother must have been taken to the spirit world with the others. The Avatar will surely find him."

"But I'm right here," Sokka said. No one heard him.

What followed was one of the worst, most confusing days of Sokka's life. And that was saying a lot, considering his tribe was mired one-hundred years deep in war, and he had spent the last few weeks traveling with the Avatar.

No one could see or hear him; No matter what he did, or how loudly he shouted.

His hands would pass right through objects if he tried to pick them up—and he would pass right through people if he didn't watch his step.

By lunch, he found out he could just as easily pass walls like they weren't even there—that was good because people had an annoying habit of closing doors behind themselves.

Sokka was a man of science, and science told him that the spirit had done some magic mumbo-jumbo on him. It must have known how much he hated to be ignored, and had inflicted on him the most annoying punishment known to man.

… Although there were no signs of the other villagers who had been "kidnapped". Maybe they were as invisible to Sokka as he was to everyone else.

"I wasn't kidnapped," Sokka muttered. "I was blasted."

For lack of anything else to do, he followed behind his sister like a polar dog puppy as she recovered Sokka's lost boomerang and searched for Aang. He rode in the back of Appa's saddle — Appa and Momo acted like they couldn't see him either, which didn't make sense. Weren't they supposed to have animal instincts?

He was there when Katara finally found Aang, who was meditating on top of a bear statue.

He watched, making witty, sarcastic comments no one but him could hear as they waited the day out. Hopefully, whatever Aang was doing in the spirit world would fix this.

It had been more than half a day since he went invisible, and he only realized he wasn't the least bit hungry or thirsty when he watched Katara dig around in his pack for a his stashed seal jerky.

"Hey, that's mine! I knew it wasn't Momo who was sneaking around in my pack. You're so busted!" he fumed. "That's my special jerky stash. No sisters allowed!"

But, considering how sad and lonely Katara looked, he figured he'd allow her some of the good jerky. This one time.

By evening, the tattoos on Aang's body dimmed. He woke and told Katara he had been in the spirit world, but hadn't seen sign of Sokka.

"Because I'm right here!" Sokka complained. "Hello! Open up your ears, Avatar!"

The monster roared in the distance, back towards the direction of the village. The sun was going down and it was back on the attack.

"All right," Sokka said, reaching for his boomerang only to remember he didn't have it with him. Well, whatever. His mind was sharper than any boomerang. "Round two. Let's do this."

He hitched a ride on Appa, and was startled when Katara stood with Aang against the monster. But before Sokka could think of what else to do (like give the monster a piece of his mind) Aang grabbed up an… acorn, of all things.

"You're the spirit of the forest," he said, and wonder upon wonders the angry monster actually stopped to listen. "I was hurt and angry when I saw how the forest had burned, too, but then I saw this. The forest will return, Hei Bai."

Yeah, sure. In like a generation, Sokka thought.

However, the monster somehow must have thought this was a good answer and shrank down. Suddenly, it was a cuddly looking panda-bear. It turned and wattled into the forest.

… And people started to step out of it. The lost villagers, looking both bewildered and happy.

Sokka watched, heart in his throat, as Katara rushed forward, calling for him.

"Katara… I'm right here."

Not seeing her brother anywhere in the crowd, Katara turned back. "Aang, where's Sokka?"

"I don't know." Aang scratched the back of his head. "I'm not sure the spirit actually kidnapped him. It sort of roared and…" He stopped and went very pale.

"What?" Katara asked.

Sokka, though, had a bad feeling he knew where this was going. "No. You're wrong, Aang."

The airbender looked down at his shoes. "Hei Bai was really angry when Sokka attacked him—"

"I didn't attack him. I was defending you!"

"Katara, for a second… it looked like Sokka was… was kind of splintering. I had thought he was sort of knocked into the spirit world, but what if… What if he—"

"What are you saying?" Sokka yelped. "I'm not dead. This isn't death!" His mother always talked about a place beyond. Not a place right here. Plus, everyone with sense knew ghosts weren't really real. They were just stories told to scare toddlers.

Katara shook her head, her hand coming up to touch her necklace. "No… No, you're wrong. The Hei Bai spirit took my brother and so it can give him back. Go back to the spirit world and tell it—"

"I can't!" Aang cried.

"Why not?" Katara and Sokka yelled in unison.

Aang took a breath. "Because when I was in the spirit world, Roku told me I had to meet him at his temple during the winter solstice. He has a message for me, and it's really, really important I meet him."

"The winter solstice?" Sokka repeated, hand coming up to slap his own forehead. "Aang that's only two days away."

"That's two days away," Katara said.

"Hey, I just said that!"

Aang looked down again. "Maybe… maybe Roku will know where Sokka is, and how I can get him out of the spirit world?" Though to Sokka's ears it sounded like he was just guessing.

Katara, however, managed to look both hopeful and doubtful at the same time.

"Or you can go back into the spirit world now," Sokka suggested, "and we can head off to Roku the second I'm back to normal!" Of course, no one heard him.

"Where is this temple at?" Katara asked.

"That's just the thing…" Aang said. "It's in the Fire Nation."

Sokka and Katara made identical faces of horror.

Had Sokka actually gotten a vote, it would have been to stick around and trying to get him see-able again.

But he didn't get a vote, so off to the Fire Nation they went.

It was terrible.

Sokka, it turned out, didn't need to sleep. He didn't even feel the urge.

Aang said he was going to keep watch as they traveled, but nodded off an hour in, leaving Appa to fly by his lonesome without anyone steering him. And as much as Sokka yelled, stomped around, cursed, and flailed his arms, he couldn't wake anyone up.

Not even when a blockade of Fire Nation ships came into view.

Luckily, good old Appa made an alarmed groan which startled Aang awake. Then Sokka had to sit back and watch in (not so silent) horror as they all dodged flaming boulders.

Why were the Fire Nation blockading their own waters, anyway? Who were they guarding it from? The non-existent Earth Navy? And that lone ship down there… was that Prince Zuko's ship following them, too? Great.

Somehow Appa made is through all the fire and rocks to Roku's Temple Island just as the sun was starting to sink to the horizon.

… Then it turned out the Fire Sages who manned the temple were treacherous, because they were in the Fire Nation. Of course they were.

Except for one named Shyu, who Sokka didn't trust at all. Not that anyone listened to him.

He was so sick of this.

No paid attention when Sokka suggested making it look like the locked fire doors had already open, either. Luckily, Shyu eventually came up with the same idea.

They were almost in the clear when Zuko turned up out of nowhere, of course, holding Aang like he had caught the biggest fish in a hunt.

"Let him go!" Sokka yelled, frustrated almost beyond words.

"Or what?" Zuko sneered.

That caught Sokka short. "Wait, you heard me?"

The evil prince didn't respond, but a look of confusion flickered over his face. His yellow eyes stared straight at Sokka. Not past him, like everyone else.

Then Aang took the opportunity to flip Zuko over his shoulders and dash into the temple doorway as it was closing.

Sokka laughed aloud.

Then… things got even more complicated as Zhao showed up, flanked by like twenty other fire benders. Wow. This vacation to the Fire Nation officially sucked. Sokka wanted a refund.

The newcomers grabbed Katara and Shyu and tied them up to a nearby stone column. To Sokka's surprise, they did the same with Zuko.

Zuko's eyes kept flicking to Sokka. He was clearly puzzled why everyone was acting like he wasn't there.

"Hey," Sokka said, walking up to him. "You can see me?"

At that moment, he accidentally stepped in the path of a guard who walked through him. Zuko's eyes widened—well, eye. The scarred one didn't do much of anything— and shook his head at Sokka, looking alarmed.

"Aha!" Sokka exclaimed. "You can see me! Awesome. Tell my sister that I'm here."

Pinching his lips into a thin line, Zuko looked away.

"Hello! I know you can hear me!" Sokka stepped in front of Zuko's line of sight, only to have the prince turn his head the other direction. Sokka balled his hands into fists. "Come on, you soulless jerk. This costs you nothing!"

He was interrupted by Zhao who came over to do a little Zuko tormenting of his own. "This is my lucky day. I'll return home with the Avatar and the traitor prince…"

Traitor prince? Sokka had no idea what that was about, but as he watched them bicker back and forth he realized: Wow, aside from Zhao tying up Zuko… those two really hated each other.

As the sun finally set, the doors to the temple opened. Katara screamed Aang's name.

Only Aang wasn't the one who stepped out.

And that's why everyone with sense fears angry Avatars, Sokka thought a few moments later as the floor crumbled under them and gouts of actual lava boiled up. In a nifty trick of firebending, Avatar Roku vaporized the chains holding Katara and Shyu—and Zuko, for some reason. Huh. Can't account for taste.

Zhao's men were in chaos, running for their lives.

The last sliver of the sun dipped below the horizon at last, and the specter of Roku disappeared to reveal… Aang.

"Aang!" Katara and Sokka rushed forward, but only Katara could catch him before he crumpled completely. "Are you okay?" she demanded. "What did Roku say?"

Aang looked up at her, and his gray eyes were haunted. "I'll tell you when we're in the air."

"But what about Sokka?"

Aang shook his head. "We didn't even get to talk about Sokka—"

"WHAT?!" Sokka was so frustrated he could scream. "Aang, come on! What am I, chopped seal liver?"

"… what Roku told me was worse," Aang finished.

Katara looked taken aback, too. Then her lips firmed and she nodded. Appa groaned from where he hovered by the window. The temple was sinking into the volcano. They had to leave.

A flash of movement caught Sokka's attention. Zuko was escaping out the back, leaping over a literal river of lava to get to safety.

And he was the only one who could see him.

Sokka felt wrenched by the decision, but he wasn't honestly sure his sanity could take another night of being ignored. And if Aang wasn't even going to ask about him… it was up to Sokka to follow any lead he had.

"Take care of my sister," he told Aang. Then he pulled away and pelted after Prince Jerkbender.