Author's Note: We're getting to the exciting stuff, guys! You know. Slowly but surely. ;)


"Leo! I have a visual!"

"Where is she, Donnie? Fast!"

Fingers clicked across a keyboard in a rhythm so rapid it sounded more like a hum. "The corner of Main street, across from the old Purple Dragon place!" he told his brother in a rush. Leonardo only gave a brief affirmative before the communication was momentarily severed, T-Phone tucked into his belt and feet pushing off the rooftop, sending him tumbling down into a soundless roll.

In moments, he was joined by Raphael to his left and Mikey to his right. The youngest brother pointed. "I see her, Leo! She's attacking some people in front of the antique shop!" Leo cursed quietly and put on an extra burst of speed, his head low and his eyes blazing.

He dropped down to the street just in time to see a Foot ninja go flying past, and when he turned to follow the movement, he saw it wasn't a bot, but a person – or, at least, it had been. Now it was a jumbled mess of misplaced bones and stomach-turning leaks. Leo's gaze snapped back to the street at a loud, menacing hiss.

Several feet away, a series of heavy mechanical clinks alerted Leo to the presence of Metalhead 2.0. Not nearly as able-minded as its predecessor, this one operated with Donnie as its eyes and ears from deep within the lair. It raised an arm cannon, prepared to take down the mutated snake that had once been Karai if necessary.

"No no!" Leo waved an arm at the machine, even as the serpentine mutant advanced on him, not a hint of recognition in its countenance. Raphael and Mikey dropped down next to him, weapons brandished even as they stood still, awaiting Leo's order.

"Karai.." Leo stepped forward cautiously, his hands free of blades. "Please, just... stop and talk to me for a minute."

"Leo," Raphael interrupted, his eyes sharp. "More Foot -"

"Take care of them."

"But Leo -"

"Take care of them!" Leo rounded on them. "I don't care what you have to do. Just keep them away." The brothers nodded in unison and darted to the end of the street. Karai hissed half-heartedly as they passed her, but made no attempt to attack. Instead, she looked back at Leo with a flick of her tongue and slithered ever closer. Behind the two mutants, chaos reigned. More Foot, both metal and flesh, were scrambling over debris and bodies to try and reach Karai. MetalHead turned on them with blasters the size of actual cannons.

Leo glanced uncertainly at the battle and then turned back to Karai, only to find her inches from his face. His eyes widened, but he forced himself past the fear.

"Karai... Please, I know it's hard, but listen to me.. You have to come with us. We can help you."

The clamor from the battle faded to the back of his mind and he stepped forward, extending a hand to her. The mutant jerked back, eyes flashing and for a moment, Leo thought she might attack. But he didn't remove his hand and it took only one more step forward to brush it over her snout and turn her face gently to look at him.

There – There it was. She knew him, Leo thought wildly. A thought confirmed when, with great effort, Karai leaned into his touch and closed her eyes. "Leeoo..."

"Just come with us, Karai. You'll be -"

An explosion rocked the asphalt beneath them, spooking Karai into snapping her face away and hissing in the direction of the battle. TigerClaw and the others had joined the battle and now Leo had no choice but to join his brothers. He turned back to face Karai, his blue eyes wide.

"Just – Just go to the lair if you can -"

But it was too late. The moment was broken and Karai's next motion was to snap at him and then slither away. When Fishface attempted to stop her, she caught him between her jars and hurled him into the nearest building. Leo watched as the mutated teenager lurched back, as if in pain. An inhuman shriek escaped her, a terrible, heart-wrenching scream of both pain and fear that had her throwing herself into vehicles and buildings with incoherent, guttural noises.

"Karai, stop!" Leo pleaded, but it was no use. Every time she moved, it was to slam into an unyielding surface, as if she might beat the cruel mutagen out of body. When six Foot soldiers made it through the rabble and jumped on her in an attempt to get her to the ground, Leo let out a shout and rushed forward in a rage, cutting them down without a single moment's thought to whether they were robot or human.

Karai escaped their clutches and cried out, her eyes feral. Finally, without so much as a glance in her savior's direction, she disappeared around a corner. Leo gripped his katana with trembling hands and the next unlucky Foot soldier to cross his path became an example in how quick deaths can be just as unpleasant as slow ones.

"... Leo?"

He turned swiftly to face his brothers. TigerClaw and the others had disappeared. Authorities were blazing their way down the street. "We gotta go, bro." Raphael nudged Leo lightly in the shoulder. He looked up at the night sky, where stars twinkled on, unaware or uncaring of the conflict below.

"We gotta go."


Donatello spent the rest of the night pouring over his notes on Karai's mutation.

"She's becoming more... manic," he murmured lowly to April. He frowned at the data in front of him, his fingers curling over the dry sheets. They rubbed unpleasantly against the newly formed calluses on his human fingers. "I don't know if it's the mutagen or the serpent DNA, but she's definitely less aware than she was just a few weeks ago."

April leaned her head in her hand, a matching frown on her face.

"Do you think she'll continue to get worse?"

"Almost certainly," Donnie tossed down the papers and turned to face her. "I mean, think about it. Most of the people we've seen get mutated were already aggressive, already willing to hurt people to get what they want. But others?" He shrugged. "Like your dad, for example. Sure, he didn't hurt you, but after he was mutated, he had no problem attacking other people. And if he'd been allowed to continue as a mutant, who knows what might've happened? He could have lost his memories of you completely."

Donnie eyed his beakers thoughtfully. "Right now, Leo is the only one she recognizes. He says she spoke to him tonight. That means she still has time." He rubbed his eyes. "But how long? I have no idea."

April hummed. "What about your work at Stockman's lab? You've been there for a few weeks. Have you made any progress?" she asked, twirling a pencil in her fingers.

"Well yeah," Donnie leaned back in his chair. "But not as quickly as I'd like, of course. It took me forever to make that first batch of retro-mutagen. And thanks to that moron Stockman, this is taking twice as long." Stepping away from his seat, Donnie moved around April with a thoughtful touch to her arm. She turned to follow his movement and snatched his fingers.

"You'll get it," she told him confidently.

Donnie's lips quirked a little. "I hope so," he replied quietly, sighing deeply in his chest, even as he squeezed her fingers and pulled her closer. And then, just as he had done a hundred times before his accident, he stooped low enough to put his forehead on her shoulder. With his eyes shut and the world around him dark, it was easy enough to allow himself to slip into a moment of peace.

When he pulled his head up once more, April reached up to brush a thumb over his jaw thoughtfully. At first he thought she might kiss him, and when she pulled back her hand, his eyes were instantly drawn to her lips.

Until she stuck her finger in her mouth and then pressed it into his ear. "Wet willy!"

"ACK! April!"

"Ah-haha!" April dashed off, leaving Donnie to blink out of his haze of confusion – and then take off after her.


It was a few nights later when it happened.

It was inevitable. He knew, as soon as he entered Shredder's lair and effectively caught his attention, that he would be investigated, for lack of better word. With every passing day, he brought more and more work to Shredder's attention. Sure, he didn't have the retro-mutagen yet, but plenty of his work provided for the Foot clan. He'd created better mutagen trackers for them using the insanely advanced equipment in Stockman's lab, as well as a more potent, controllable version of the original mutagen. Most of these had been by-products of his actual research – every new failure was a discovery in disguise, after all – but Shredder was relatively pleased with them nonetheless.

His training was a different story. He'd thought to force himself to look unskilled in the dojo, but honestly, he didn't need to fake it as much as he'd thought. The style being taught was so altogether different from what he had beaten into his body years ago that it felt like a new art form altogether. He had tried various weapons, but as he'd learned when he'd made an effort to get familiar with his brother's artillery, he was useless at most of them.

There had been staff-like weapons at Shredder's dojo, but he had steered clear of them, only using a few in during brief, bumbling exercises to reiterate his ineptitude.

Stepping into the warm summer night lifted some of the heaviness in his chest. Donnie moved off the sidewalk, his hands in his jeans and his eyes raking over the city streets with the sort of keen awareness that was bred from his lifestyle. There was no such thing as an "empty" New York City street, so even as the hour was very late, people milled around him in business as usual.

Even so, he picked up the movements darting around the shadows behind him. The telltale signals that accompanied a sleuthing stalker. Someone was following him from Shredder's lair and it wasn't one of his brothers. In fact, it wasn't one of anything. It was several.

Donnie kept walking, occasionally nodding to people as he passed. He kept pace, but didn't hurry, even as his mind anxiously turned over his alternatives. Obviously, he couldn't go back to the lair. If these spooks were Foot bots like he thought, they were waiting to see where he was heading.

April and Casey's places were both out of the question, too. Shredder knew them.

Just as he was beginning to truly panic, a memory struck him like a lightning bolt. Grinning at his own stroke of brilliance (he really ought to remember to pat himself on the back more often), Donnie changed direction and skipped over the edge of a sidewalk to cross the street. He passed a few shops, some of which were still open with a dim white light and bored looking store clerk. Other stores and their accompanying stands stood empty, bare of both product and salesperson. A scantily clad woman with a great deal of smeared lipstick gave Donnie a seductive smile as he passed, prompting him to wave lightly before continuing on.

He stepped into the area known as China Town, which sat just above the subterranean lair. But it wasn't the lair he was heading towards. Donnie paused in the street, looking both ways as if to check for traffic. In reality, he was double-checking to make sure he was in the right place. Then he hopped down from the curb and passed in front of Murakami's restaurant, only to jet across the road to a lopsided building that housed three small apartments. Donnie paused at the door to the bottom floor and beat his pockets as if he were looking for something. Then, with a shrug, he stood on his tiptoes and pulled a spare key from the top of the frame. He used it to open the front door and then entered with ease.

One inside, he shut the door – and collapsed against it with relief.

A quick glance at the windows revealed a bit of moonlight sliding through the shades of heavy blinds. Donnie rushed forward and straightened them, further pulling down curtains and securing them. A quick search around the apartment confirmed he was alone.

After several moments of fumbling, Donnie found a candle and a match, and a few minutes later, he had the small apartment lit well enough to navigate. Sinking onto the low bed with a deep sigh, Donnie glanced up and around.

Murakami-san, the kindly old Japanese man who owned their favorite restaurant, had left a few days ago for a trip back to his home country to visit family. Donnie wasn't exactly sure how long he would be gone, but obviously it was for a while, because he'd temporarily closed his restaurant and asked April, his trusted friend and customer, to water his plants and feed his cat. She'd mentioned it to Donnie just yesterday, and thank god he'd been paying attention instead of staring at her mouth like he'd been doing only seconds before.

Unfortunately, Murakami-san – what with being blind and all – didn't have a single light in the entire place, all the sockets bare of bulbs and the walls equally blank. Everything else in the apartment was simple and plain, or indicative of his homeland. A screen bearing a scene of Japanese countryside separated his floor-level bed from the rest of the rest of the studio apartment, his couch and radio the only other two distinct items in the living room area. He did have a kitchen bursting with strange instruments and tools, though, which Donnie didn't find surprising.

Everything else was shelves of cookbooks – mostly in Braille – or his dozens of plants. A tall bamboo plant was the most prominent, sitting next to his bed and looming over the pillow with dark green leaves. Several small herbs dotted the counterspace, filling the area with an unusual blend of not unpleasant smells.

Something brushed Donnie's leg and he jumped, expecting a Foot soldier. The "soldier" in question meowed at him, blinking yellow eyes and then curling in his legs again. Donnie exhaled and fell over on the bed. Now that his heart had stopped pounding, he may as well rest.

It wasn't safe to go back to the lair just yet.


He chanced it during the day.

Shredder's goons typically didn't come out in the light hours, so after taking a nap at Murakami's place and then checking for Foot ninjas, Donnie left and made his way back to the sewers. He expected his brothers to all be asleep, but when he slipped quietly into the kitchen, he saw Raphael sitting at the counter. He looked tired, but he popped out of his seat when Donnie entered.

"Dude, where have you been? We thought you were coming home hours ago."

"Sorry," Donnie dropped heavily onto a stool. Three hours had not been enough sleep. "I had some company when I left Shredder's lair last night. He had four Foot ninjas following me. I had to backtrack to Murakami's apartment."

Raphael raised a brow ridge. "Well, damn. Do you think he's on to you?"

"No, but I do think he's suspicious. Paranoid, even. He's kinda loopy," Donnie made himself a cup of coffee. "Incase you haven't noticed."

Raphael relaxed and smirked. He shrugged a shoulder, his eyes moving to the fridge. "Well, I saved ya some pizza."

"Really?" Donnie grinned a little.

"Yeah," Raph smoothed a hand over his hairless head. "And I had to put Mikey in a chokehold to keep him away from it, so you better eat it. I don't care how old or soggy it is." The two of them took seats once more at the counter, both leaning heavily on their elbows out of exhaustion. Donnie nibbled at his food. "You look like shit," Raphael observed.

Donnie glanced up from his food and blinked warily at his brother. "I haven't had a decent REM cycle in days," he admitted, tearing off a piece of crust.

Raphael waved a hand. "You never sleep good."

"Well."

"Well, what?"

"I – nevermind." Donnie smiled and sipped at his coffee.

Raphael ignored him. "You know what you should do? Take some Nyquil. That stuff'll knock you on your shell."

"How do you know?" asked Donatello. "I've never give you cough syrup before." Nor did he think Raphael would seek out medicine on his own. He was The Worst Patient in terms of personal care. Donnie had once spent an entire week chopping gummy bear vitamins into tiny, microscopic pieces and slipping it into his brother's food just to try and get some nutrients into him.

Raphael chuckled, "Oh, I know. But I saw on tv that it makes you sleepy, so I put some in Mikey's cereal the other day. It was the best thing ever, he just went -" Raphael slammed a hand onto the counter. "Bam! Right into his bowl."

Donnie's shoulders trembled with laughter. "Why would you do that?"

"Uh, because he talks too much?" he paused. "And because it was funny. He did almost drown, though."

Another pause and then both of them dissolved into the kind of laughter that caused stomach-aches for hours.


Michelangelo made a face.

He'd sucked, chewed and licked his way through a cherry popsicle, but now he was only left with a red-stained stick and the unhappy taste of wood in his mouth. Tossing it into the trashcan nearby, he turned on a heel and headed into the living room area. Raph was mashing away on a video game controller and trying to goad Leo into battling him, but the leader in blue was stoic from his place on the couch. He shrugged off Raphael's jabs and left the room without a word.

Mikey heard his brother sigh once before turning back to his game.

Scrunching his noise, Mikey turned to go to the kitchen – maybe he'd just eat another popsicle and feel better – when he paused at the door to Donnie's lab. Glancing around and then stepping further inside, he spotted Donatello at his table. There was a loud beeping sounding rhythmically, and he knew it was the timer from one of Donnie's burners. His brother was standing right in front of it, left hand closed around a liquid-filled beaker, but he made no motion to cut it off.

Instead, he stared, shoulders hunched and fingers tight, his expression too far away for Mikey's liking. Even as the alarm continued to sound, Donatello remained unmoving. After a few moments, Mikey realized Donnie's hands were shaking. And then -

Pop! Crash.

The beaker in Donnie's hand exploded, jarring him out of his stupor. Mikey frowned and edged closer to the lab door, trying to stay out of sight as he watched his brother move slowly, as if underwater, reaching over to turn off the beeping alarm and then fall still once more. He glanced numbly at the broken glass and then at his hands, jagged with small cuts. Instead of tending to them, he leaned against the table and let his gaze fall on the constant flame on his burner.

His eyes fell unnaturally still, and as Michelangelo watched, his brother reached forward – and pressed his hand into the flame.

"Dude, stop!" Mikey jumped forward and snatched his brother's hand away. For the love of god, did he have to keep everyone else sane around here? Since when was he the one trying to force logic and reason on people? This place was going insane.

It made Mikey want to cry. He pressed it back with great effort.

"What's wrong with you?" asked Mikey, his voice trembling. He led his still apathetic brother away from the flame and blindly reached for the first-aid kit. "What's wrong with everyone?" he muttered, taking out the burn cream. His brother's hand looked like the top of a dresser that had been melted by an unattended candle. It had to hurt like hell, but Donnie hadn't said a word. Something in his face reminded Mikey of that day he'd caught him "cutting his fingernails" when in fact, he'd actually just been slicing his fingers open.

After wrapping up the hand, Mikey sighed and met Donnie's blank gaze. He didn't understand. Donnie had been fine just a few hours ago!

"I think... I think you need some help, Donnie. You haven't seemed right lately, bro."

As Mikey spoke, Donnie pulled his injured hand away. "I'm fine," he said finally, his brows furrowed. "I don't need help."

"You do. Something's wrong with you."

Red eye narrowed into slits. "Nothing is wrong with me," growled Donatello.

Mikey balked at the contorted glare, his feet instinctively taking a step back. "Dude, yes, you need help. It's okay. I think.. I think your accident did something to mess you up, but..."

"Don't tell Leo," Donatello pleaded, and the swift change in tone jarred Mikey – he was almost crying, his eyes wide and teary. "Don't tell anyone, please. I'm okay. I'll figure it out."

Mikey swallowed tightly. "Please, Donnie. Just -"

"I can figure it out!" exclaimed Donnie, wrenching himself away from Mikey and stomping back to his table. "I can do it. I can do it by myself. I don't need you here, telling me that something is wrong with me, nothing is wrong with me."

Donnie gripped the edges of his lab table. "Nothing..." his voice dropped to a whisper. "I … I hope nothing.. is wrong with me."


It was late.

Leonardo had made it last rounds in the lair, his eyes sweeping over every entrance and dark corner with practiced ease. It was really an unnecessary measure for a place as guarded as their lair, but it had become a comforting routine to him. And maybe, a tiny part of him hoped that Karai had regained enough sense to make her way back here, maybe she was just waiting out in the tunnels and needed him to come let her in.

That wasn't the case. But it was a nice thought.

He stopped by the door of the lab and peered inside. By the light of Donnie's desk lamp, he saw his seemingly human brother, slumped over on his desk – and sound asleep. Leo allowed himself a small smile. Donnie had obviously been working himself to the bone and now his exhaustion had finally caught up with him. Stepping inside the room with a silent tread, Leo crossed the room and came to stand at Donnie's desk.

His brother was curled on top of a pile of textbooks, data charts and page after page of tiny scientific text, none of which appeared atypical of the area. However, as he raked his eyes over the contents of the desk area, his lips pursed at a frown. Reaching down, he turned a heavy open text-book with a green fingertip until the text faced him.

It was a medical book, Leo noticed, one he hadn't seen before. It had long pages of jargon he didn't even hope to understand, and one lengthy paragraph in particular had obviously caught Donnie's attention, because it was highlighted and circled in thick, heavy pen. Leo didn't understand all of it, but it his brother had underlined things like temporal lobe and brain damage. On the area around the footnotes, his usually neat handwriting had melted into a scratchy, frantic scrawl.

Fire fire fire fire fire.

Visions?

Red. Red Red Red. Fire. WHY

Mutagen cross-reference? 2.3 – MRI?

WHERE IS IT?

No sleep!

Red. Red. Red.

Mutagen effects on the brain – why blood?

F – K

Other words had been written upon a time, but they had all been scratched out with dark, heated strokes, so worn and overused that they'd bled through the other side of the glossy book page. A snapped pen rolled lazily next to the spine of the book, ink still rolling out of its broken tube. Leo's eyes slowly lifted to his brother's hands, clenched even in sleep, stained with black ink.

Leonardo dropped his eyes once more to the text. Then he slowly lifted the corner and closed it, his gaze on his sleeping brother again. With a soft weary sigh, he pushed the book away and bent his knees. Hooking one of Donnie's arms around his neck, he lifted him out of the chair and walked them both to the door.


Leonardo watched Donnie all the next day, but whatever was going on with him, he didn't show an ounce of it. Which might have had something to do with the fact that April was there with them, officially out of school for the summer and laughing playfully with his brothers as he observed them.

He didn't miss the strange hitch in Michelangelo's gaze whenever Donnie came near. Nor did he miss Raphael's careful eyes watching their brother, just as he was, as if he were waiting for the other shoe to drop. They all talked and laughed, April and Donnie most of all, but he knew his family well enough to know that something wasn't right.

"Hey, I found and fixed up a homemade ice cream maker the other day," Donnie volunteered to April. "You want to go make some ice cream?"

"Heck yeah!" she cheered, jumping up with a grin. Donnie bound after her, looking like his normal self for all the world. Raphael and Mikey hesitated only for a moment before racing off after the other two, leaving Leonardo alone in the living room.

The lone turtle leaned back in the beanbag chair, his hands idly turning over a small silver blade in his hands.

Whatever was going on, his brothers were starting to see it. But April wasn't. Donnie was hiding it from her best of all. Leonardo glanced at the blade in his fingertips and drew one careful digit down the length of it.

No, whatever was happening to Donatello had him slipping up in front of his brothers... but a different person altogether with April O'Neil.