Author's Note: 2012 verse, canon-divergent. Starts during Season 3, after the turtles and their allies have taken back New York City. Donatello-centric.

Prologue

Donatello hurried through the dark tunnels of the sewers. The meeting point was only fifteen minutes away from his home, but he had been delayed. His brother Michelangelo had decided that he needed his company, and offered to help him with whatever project he currently had.

Donatello couldn't tell him that his current project involved meeting with an old enemy, and had pretended that he was in the process of cleaning up his lab - a task he was positive Michelangelo had no affinity for. Alas, his brother was persistent, and Donatello had been unable to sneak out before the beginning of Michelangelo's favorite ongoing show.

Brushing him off only to leave the lair would have been strange at best, suspicious at worst - and if there was something Donatello absolutely didn't want at the moment, it was to make one of his brothers suspicious.

The turtle mechanically brushed his bō staff. He doubted that he would use it - his interlocutor had made very clear what would happen if he did - but he still felt reassured by the familiar weight of the wooden weapon.

He arrived at the meeting point, an intersection between three different tunnels that would have been perfect for a trap.

Well, the precaution was useless. He was already trapped.

"Welcome, turtle."

The feminine voice made him wince. He turned around to meet the incomer, a young teenager with dark hair, a plaid skirt and giant boots.

A girl that had been April's best friend before they all learned, in the most dramatic of circumstances, that she wasn't human at all.

Donatello looked bitterly at the robotic body of one of the most dangerous Kraang he had the dubious honor to meet - Kraang Subprime, the only one that mastered the English language.

These days, he went by the name Irma.

Donatello's hands clenched to fists, and maybe they moved a little towards his back, because Irma clicked his tongue.

"Oh, no, don't even think about it." She smiled. "Not if you want your brother to live - which you do, correct?"

Irma's cold look was piercing him.

"You poor creatures. You care so much, it's disgusting."

Donatello swallowed hard and fought to avoid telling her just what he thought of her actions. Yelling at an enemy who held all the cards was rarely a good idea. "I'm here. Let's finish this."

The inhuman girl smiled again. "I can't believe you didn't move," she cooed. "Did you think I would never dare to come back?" She squealed, opening her robotic arm to show a touch screen and a red light flashing. "And now, one move and one of your brothers dies. Isn't it great?"

Donatello closed his eyes briefly. Why, indeed, had they considered that their old lair would be safe, when it had been discovered and invaded by an alien army only a few months ago? Granted, they had ultimately defeated said army - too bad that one of them came back to haunt his family. To haunt him.

He didn't even know if it was Leonardo, Michelangelo or Raphael who had been drugged and implanted with the tiny bomb. As far as he could tell, all of them seemed fine.

"Why do you need this data?" he asked. "Invading Earth didn't work last time."

Irma shrugged. "I have new plans."

Donatello considered her. She sounded more calm and casual than he had expected - the Kraang Subprime he remembered was brutal and violent, and once discovered, immediately switched to full battle mode.

But Irma had fooled April and her telepathic abilities for an entire year.

Donatello didn't know what to think, and chose to change the topic by asking another question that was burning his lips.

"Why me? There are so many mutants in New York."

The creature in front of him rolled her eyes. "It felt appropriate, considering our history. Besides, how many mutants have studied biology? I need a test subject able to precisely describe his feelings. It's important for the accuracy of this experiment."

Irma took a small vial from one of her pockets and held it out to Donatello, who took it with great reluctance.

"Remember," she said coldly. "One drop every day."

Donatello took the vial.

"I will remember." He watched the blue liquid inside the vial, his throat dry. "How can I be sure that it won't kill me?"

"You can't. Believe it or not, this time I don't intend to kill you - unless you make me." Irma pushed her glasses up her nose. The illusion was perfect - even now that Donatello knew better, it was hard to believe that she wasn't a human teenager. "I'll be expecting your reports to be detailed and precise. And needless to say, not a word to anybody else."

She waved at him as if they were the closest of friends. "Have fun!"

Donatello watched her depart, his heart heavy. She had promised that everybody would live if he followed her instructions, but he knew she was going to double-cross him at some point. It was only a matter of time.

But what else could he do except to buy some time, when one of his brothers was now a ticking bomb, and she was the detonator?

Author's Note: I was surprised when the turtles kept their old home after the invasion. After all, it had been utterly compromised. That plus my will to explore different threads in the cartoon's lore lead to this story.