This is, without a doubt, the craziest crossover I've ever written - and speaking as someone who's jammed both GLaDOS and Mr. Bonestripper into their stories, that's saying a lot. Like all my crossovers, I've tried to write this so people unfamiliar with either of our two special guest doctors will be able to follow along - but, like all my crossovers, it's a hell of a lot funnier if you're familiar with the characters that I've dragged kicking and screaming into my universe.

Dr. Horrible (from Dr. Horrible's Sing-Along Blog) is, without a doubt, the star of the best comedy musical about an evil genius ever. You can catch his exploits at drhorrible dot com.

If you're into goofy Batmanesque stories (and you must be, or you wouldn't be reading this), you need to be reading Dr. McNinja. You have no choice in this matter. Go to drmcninja dot com or suffer my fangirl wrath. (The current story's a great place to start reading! Also, don't miss the alt-text.)

Usually, I'd give you a spoiler alert right here. This time, though, there's no excuse for not being at least passingly familiar with the source material. It's right there on the interweb! I'm prepared to sit here patiently until you go read it.

I mean it. I have City of Villains all booted up, ready to go, and a shiny new Arachnos Widow to level up. I can wait all day.

You're back? Good. On with the story!

Jonathan Crane was not a thief.

Rather, he wasn't a professional thief. Oh, certainly thieving played a large part in his life - how else was one to fund a criminal enterprise based on the manufacture and distribution of highly expensive toxins? - but he wasn't the sort to take pride in his thievery, as if it was the only worthwhile thing he'd ever done. Stealing things was merely one of those tasks that had to be done in order to bankroll his real work.

Aside from money, there were other obstacles standing in the way of his research. The most pressing obstacle was and would always be the Batman, that over-muscled vigilante who knew the power of fear but refused to share that knowledge in any scientifically meaningful way. It seemed that he'd spent half his professional life running from Batman, cursing the fates that had doomed him to whip-thin frailty instead of a frame like a grizzly bear. He had to waste countless hours plotting ways to slip beneath Batman's radar, because in a one-on-one fight Batman was certain to win.

Or was he?

Not if Dr. Crane had anything to say about it - and, in a few more minutes, he'd have some very definite and gleeful words on the subject. At the moment, he was lurking in the shadowy woods surrounding a small, cheerful-looking doctor's office. Twigs bit into his kneecaps through his shabby, much-mended pants as he squinted at the tiny glowing dial of a watch on his bony wrist.

Three...two...one...On cue, a fireball thumped up into the black night sky. And, as he'd hoped, the door on the other side of the building almost immediately slammed open, followed by the hurried thudding of feet as the doctor and his assistants scrambled into their car. The smallish black sedan, almost invisible behind its blinding headlights, screeched down the short forested road and disappeared.

Perfect. Crane rose to his feet and padded toward the building. It was almost painfully easy to break in - the windows had normal locks, and he'd come prepared with a little circular glass cutter in order to snake an arm inside and unlock them - and it was easy to slide himself in through the narrow gap of the open window.

He trotted quietly down the hallway toward the lab. The handle of the door turned easily under his hand. They hadn't even bothered to lock it! With a tiny smirk of triumph lurking under his mask, the Scarecrow advanced into the lab to look for his prize.

This doctor, Dr. McNinja, an odd name if he'd ever heard one before (and he had - for some reason, people in Gotham named their children tongue-twistingly different names that transformed easily into criminal noms de guerre), had invented a new kind of drug. Normally, this would have meant nothing special to Crane, since he didn't pay too much attention to the medical profession any more. In fact, just a few days ago, he'd actively been trying to avoid the news being blasted out of the car idling in front of his lair. Who on earth listened to NPR at that volume? he'd wondered, too exhausted from his night in the lab to bother going outside and killing the driver.

The all-too-perky voice had blared like an bullhorn through the pillow wrapped around his ears. "...our own Dr. McNinja has stopped Rayner's drug distribution, and he's also managed to concoct an injectable "anti-ninja-iotic" or "cure" or whatever you want to call it, and is using it to "de-power" all the ninjas." Crane had immediately perked up, letting the pillow fall haphazardly to the bed. This had possibilities. "But here's the rub," the radio chirped, "McNinja refuses to let anyone handle the antidote. He won't give it to the cops, the military, hospitals, nobody. He says he's essentially created his own kryptonite, and is guarding it with extreme caution. So Dr. McNinja is injecting every single "fake ninja" personally, by appointment, in his office."

Would a drug to de-ninja someone who had only become a ninja because of a ninja drug work on someone who had become a caped and chiropterean ninja thanks to years of training? Crane didn't know, but he'd been very eager to find out.

And so Jonathan Crane, who wasn't a thief, crept into the small lab in order to make off with the anti-ninja formula that just might make his life a thousand times easier. It looked like it would be a fairly easy search, provided that the doctor kept his labels up to date. The lab tables were neatly laid out with a wide assortment of medical paraphernalia. In the corner, by the well-locked window, was a large cabinet. Crane quietly swung the doors open, a penlight gripped between his teeth, to reveal shelves with stacks of vials, bottles and packets containing everything from - he squinted - Hair Removal Gel #105 to boring old penicillin. Where was the anti-ninja drug? Long, thin fingers rattled through the shelves. There, in the far corner - what was that jar? He shoved the door open.

Whong. "Hey!" someone protested as the door rebounded off of them.

Crane scrambled backward from the cabinet, feeling for the little toxin-release button tucked inside his glove. The penlight spun to the floor, forgotten, as he shoved the breath mask back down over his face. They couldn't be back already! He slammed the door, expecting to see an angry doctor or a surprised security guard behind it.

Instead, stuck halfway through the newly-opened window like a marauding air conditioner, was a young man in a red lab coat with a pair of welding goggles shoved onto his forehead. He scrambled through, deftly unshouldering a black bag as he landed. "Hands up!" the intruder demanded, raising his arm and pointing a black-gloved fist in Crane's direction. A shiny silver gun gleamed on top of a pair of bands mounting the device to his forearm.

The Scarecrow obligingly raised his arms. His thumbs rested lightly on the pair of buttons on either forefinger that, should the intruder get within range, would send toxin spewing in wonderful clouds from the tiny tubes in the elbows of his shirt.

The newcomer gestured with the gun. "Where do you keep the cure?"

"Have you tried a record store?" Crane drawled.

"Don't get cute with me, McNinja. The anti-ninja formula!"

Crane sighed and dropped his arms, fingers resting on the buttons to release the toxin at his wrists. "So you're here for it too, hmm?"

"I said hands up!" the boy ordered. "You have no idea what this gun can do!"

"And you have no idea who you're dealing with," Crane said frostily. "I was here first. Go away."

"Who do you think you are?" the kid demanded.

Crane eased forward into the pool of moonlight, letting the dim silver rays catch the rough burlap of his mask. "The Scarecrow," he hissed.

The kid immediately lowered his weapon. "Wow! I used to read about you all the time when I was growing up!" he gushed, with the air of one meeting a childhood idol. "Laughton, right? Ebenezer Laughton?"

Crane drew himself up to his full, imposing height. "Dr. Jonathan Crane," he corrected icily.

"Dr. Horrible," the boy introduced, pulling half-a-dozen bits of shiny technology out of his bag. "How long have you been working for the ELE?"

"I don't work for - or with - anyone," Crane growled. "Go home, kid. I have work to do."

"So do I." The so-called Dr. Horrible set up something that looked like a tiny telescope on the floor, aiming it precisely at the door to the little lab. "How about this: I'll get the formula, and you can watch for McNinja to come in."

"How about this," Crane suggested, waiting for the perfect moment to strike. He'd prefer not to gas the kid if he could help it, given that terrified people were more concerned with screams than secrecy. He was certain to get caught sooner if he had to gas the brat. "I'll get the formula, and I promise not to hurt you too badly if you leave. Now."

"You wouldn't hurt me," Dr. Horrible said absently, tweaking a leg of his telescope's tripod into place. "I'm a member of the ELE. Bad Horse would stomp you into the ground."

"Why should I care about you or your horse?" Crane inquired. "I don't care what group you think you belong to. If you don't want to belong to the obituaries, you'll get out of my way."

"Maybe you didn't hear me the first time," the boy said, pulling a remote control from his pocket. "I'm Dr. Horrible. I have a PhD in horribleness!"

"Catchphrases are for people more concerned with their PR than their work," Crane fired back.

"PR is my work," the kid said, exasperated. "At least, part of it. How are you supposed to make the populace fear you if you don't tell them why they should?"

A slender finger hovered over the toxin release button. "Would you like the answer to that?" Crane asked pleasantly.

Bang. The door to the lab swung wide open as the room filled with brilliant white light. "I'm telling you, it was just like Whitestone - " a young boy's voice trailed off. The Scarecrow and Dr. Horrible turned slow, wide-eyed looks at the group filling the doorway. In the lead was a doctor wearing a grey-and-black ninja mask along with his labcoat. Beside him was a young boy, dressed in cowboy boots and denim, with a red bandana around his neck and a fabulous, luxuriant moustache growing from his upper lip. Behind them, a gorilla with a clipboard and a large brown velociraptor narrowed angry eyes at the intruders.

Then things got a little weird.

With the instant camaraderie available to all villains in the face of Justice, Crane and Horrible put off their fight in favor of surviving this one. As Dr. McNinja sprang forward, the Scarecrow loosed a cloud of fear toxin in his path. The doctor pivoted effortlessly and hurled himself to the side, leaving the toxin to harmlessly dissipate. With the bandana over his face, the young boy threw himself toward the fight, a pair of pistols gripped firmly in his hands.

Gloved fingers clacked on the remote control. Dr. Horrible's machinery blinked and fizzed inside his open black bag. The tiny telescope-esque device that he'd propped on the floor came to life with a blasting fzzzzz, spitting out a ray of blue light that froze the incoming ninja and his diminutive bandito assistant in place.

The gorilla and the raptor both tried to shove through the small door at the same time and wedged themselves in place. Snarling in fury at the intruders and each other, the two commenced a stationary wrestling match, clawing at the doorframe and screaming raw hatred at the two stunned criminals.

"Run," Crane suggested, dry-mouthed, and vaulted through the window. Dr. Horrible followed an instant later, lugging his bag of tricks and wheezing as they darted down the short road toward the highway.

"Why didn't you gas the ape?" Horrible accused as they vaulted a fallen log.

"Have you ever - " they ducked beneath a low-hanging branch, "seen a gorilla that's been exposed to fear toxin?" He had. Gorillas in mortal terror didn't cower - they charged. As for the velociraptor, well...he wasn't inclined to do anything to make it even more likely to rip his guts out. He'd had his guts ripped out before and it was not a pleasant experience.

A raaaatch of triumph rang out behind them as the window shattered, presumably allowing an exit for the doctor's associates. Horrible stuck a hand into his bag and came out with a little metallic box covered in flashing lights. He tossed it behind them, leaving it blinking tantalizingly in the middle of the road.

They ran in panting silence for a few moments. Crane could almost feel sharp dinosaur talons digging into his shirt. He darted a wild glance over his shoulder. The raptor was behind them, coming up fast on the little box.

SPANG! The forest lit up with actinic, searing brilliance as the heavy, putrescent scent of rotting fish filled the air. "What was that?" Crane demanded as they wheeled around a curve in the road.

"Fish-bulb bomb," Horrible answered, a note of pride in his voice. "It should keep the thing blind and distracted until we're away."

They skidded onto the main road. A pair of headlights in the distance was headed their way. Under the mask, Crane's face went pale as he recognized the distinctive rrrrrrr of the engine. "Down!" he barked, bodyslamming Dr. Horrible in his haste to dive into the ditch. Horrible yelped and tumbled down next to him, landing with a squelch in the same puddle of greasy mud that was soaking through Crane's pants.

"What are you -"

"Ssshhhhh!"

They could hear the raptor behind them snorting and screeching as it tried to see or smell its fleeing prey. Leaves blew up wildly around them as the Batmobile whizzed by, screaming around the corner. Thud. "Raaaaatch!"

"I think he got the raptor," Crane hissed. He glopped out of the ditch.

"Who?" Horrible asked, poking at his remote control.

"Batman!"

Horrible's eyes widened with recognition. "Him? Here?" He freed himself from the mud with a squortch and hammered on the remote control. Nothing happened. "It's dead. Come on - I know a place we can hide!"

Crane's original plan had been to walk to a motel, remove his Scarecrow gear, and book a room under a fake name like any self-respecting villain visiting a new town would do. Now, covered in mud, with Batman on his tail, that plan was looking less and less feasible. "Fine."

Voices sounded in the woods. With a shared look of panic, the pair raced away, leaving a trail of black mud splattered on the asphalt.

Dr. McNinja was used to getting what he wanted. It was hardly surprising, given his choice of career. Doctors, as a breed, tend to give the impression that they are all-powerful - and ninjas, by necessity, are just about as all-powerful as any mortal human can be. When he wanted something, he made it happen.

They say to be careful what you wish for, but very few wishes are dangerous when they're wished by a ninja doctor with a flair for properly executed pre-mortem one-liners.

The evening had been fairly quiet, for once, until that explosion blew the roof off of City Hall. Doc and his associates had rushed out, confident that they would be needed. When it turned out to be nothing more than a boring old group of pipe bombs, with no hint of involvement by ghosts, wizards, ghost wizards, vampires, midget doctors or Ronald McDonald, they holstered their various weapons and trudged back to the office. Gordito had insisted that it was kinda like the last ghost wizard, who'd had a very mean fireball spell, and he'd continued insisting that right up to the moment that they'd walked into the lab to find two strangers arguing in front of the drug cabinet.

Doc had immediately swung into action, dodging a spray of toxin by pure instinct and wheeling to confront the two intruders. Then -

The room blinked around him. The window was shattered, with a vaguely dinosaur-shaped chunk missing out of the panes of glass. His secretary, Judy, was standing in front of him, holding a severely broken weapon in her huge black hands. Doc effortlessly slid to a halt. Gordito, who was decidedly less nimble on his feet, slammed heavily into his back.

"Judy! Where'd they go?" he demanded. Judy dropped the destroyed ray gun on the floor and waved her hands. "What? What are you trying to tell me?"

"She says that the raptor went after them."

Dr. McNinja whipped around to spot the owner of that oddly familiar voice. There, in the corner of his lab, examining the door handle, was...

"Gordito," Doc hissed out of the corner of his mouth. "Am I bleeding anywhere?"

"What?"

"Am I bleeding anywhere?" he repeated urgently.

"No...why?" Gordito whispered back.

"Because I see Batman in the corner."

"Batman is in the corner."

Dr. McNinja examined the black-cowled crimefighter. He'd been known to hallucinate when he was on the brink of death - in fact, now that he thought about it, he'd been hallucinating a lot recently - and he was fairly certain that what he saw could not be real. "Seriously, Gordito."

"He's right there!"

Glass crunched behind them as someone entered through the window. Doc swiveled and backed up to keep both the window and the Caped Crusader in sight, his ninja instincts automatically kicking in to prevent him from exposing his back while his mind was too busy turning cartwheels of ecstasy and blithering about how Batman was right there, oh my god, it's Batman. Batman's in my lab...

"He's headed away from town," Robin announced, picking his way around most of the larger glass chunks on the floor. "Are there any more velociraptors around here?"

"No, just Yoshi," Gordito said proudly.

"Oh. He's yours?"

"Yeah!"

"I think you'd better come with me," Robin said. "When we drove up, he tried to charge the car. We got out of the way and he ended up ramming into a tree."

"Yoshi!" Gordito gasped, dashing for the window. "Yooooshiiiiii," he called into the dark woods as he vaulted the glass-covered windowsill and trotted around the building. Robin flashed an It's-okay-I'm-a-crimefighter smile at Doc before he followed Gordito into the night.

Batman finished his examination of the equipment on the table. "Did they take anything?" he asked Doc.

Had they? Dr. McNinja swung the door of the cabinet open and peered inside. "I don't think so," he said, nudging bottles back into their correct places. "They left the narcotics, and the - oops!" His trembling elbow knocked into a box, sending it plummeting to the floor. A labcoated arm lashed out and caught the box as a spray of loose white tubes came tumbling out of the top of it.

Batman picked one up and studied it. "Hair removal gel?"

"There's been a rash of lumberjacking recently," Doc explained, stuffing the rest of the tubes back into the box. "Nothing's missing."

"Why would the Scarecrow come here?" Batman tossed the tube back at the doctor. Doc caught it and tucked it into his pocket. This one's going on the mantel, he decided, with maybe a little sign...Batman Touched This...nah.

He dismissed thoughts of his upcoming "I-Met-Batman" shadowbox and turned his mind to the failed robbery. "Is he involved with the Bunyan hunters?"

"No."

"Dracula? I know Dracula's not very happy with me right now."

"No."

Doc brightened. "Those kids from the bar!" he declared.

"No..." Batman growled, starting to lose what little patience he had.

"That's got to be it, though!" He pulled a drawer in one of his lab tables open, revealing a gleaming assortment of little metal things capable of seriously injuring people, and began loading up his pockets. "The Scarecrow must have heard about my anti-ninja-iotic! I cured a bunch of people in the bar last weekend," he said with pride as he strapped a second katana across his shoulders. "It was all over the radio." When he looked up, Batman was gone.

Batman strode up to the Batmobile, interrupting Robin and Gordito's conversation over the bruised velociraptor. "Let's go," he barked at his young associate.

"Later, Gordito!" Robin said as he obediently leapt to his feet.

The roof of the Batmobile slid back. "So anyway," Dr. McNinja said, lounging in the passenger seat with his feet on the dashboard, "you're going to want help to catch those two, right?"

"How did you get in there?" Batman demanded.

"Ninja tricks. You know," Doc said, winking merrily.

"I don't need your help. I can handle the Scarecrow and his henchmen," Batman said icily.

"I know. But it's not just him," Dr. McNinja pointed out. "The other guy wasn't with him. The themes didn't match."

"Who was it?"

Doc shrugged. "I've never seen him before. Red coat, welding goggles, twitchy face?"

Batman mentally scrolled through his list of potential offenders. "Horrible," he said decisively.

"What?"

"Where would they go?" Batman demanded.

"Judy said they went that way, right?" Doc asked, hitching a thumb over his shoulder to point at the pitch-black woods.

"Yeah," Robin chirped. "They did."

"Then I know just who to ask." Dr. McNinja vaulted out of the car. "Things are a lot easier when you've got robots watching the city."

Batman was inclined to disagree. Still, spy robots had their uses, and if it meant they could track the Scarecrow and Dr. Horrible without walking into a trap, he would go along with it for now. With his cape trailing behind him, Batman followed the doctor.

The two sidekicks looked at each other. "Do you like beets?" Gordito asked.

"Sure," Robin said, a little baffled at the question.

"You can have mine. C'mon." Gordito checked his pistols and sauntered off after his boss. Cracking twigs behind him indicated that his raptor was limping to catch up to him. "Go home, Yoshi!" he ordered.

Yoshi, with a slightly swollen ankle and a nasty bruise on his head, let out a raaatch of disappointment and disappeared back toward the little office.

(to be continued)

Author's Note: Yay! Beets!

Direct quotes were taken from both Dr. Horrible and Dr. McNinja, specifically the radio bit from 'Revenge of the Hundred Dead Ninja' and Horrible's lovely catchphrase. Ebenezer Laughton is, of course, Marvel's Scarecrow, because apparently mashing three universes together just wasn't enough for me.

Crane's adventure in disembowelment was from Detective Comics #836. Sixty points to you if you spot the Simpsons reference!