The long corridors of the hospital at Pascula Base always smelled of disinfectant and plastic, and reminded Leo of the smell inside his spacesuit, an unpleasant association. He exchanged nods with a couple of familiar faces. Here, in this mix of alien cultures, they didn't stand out at all. It was strange how far from home they'd had to go to finally feel like they belonged.

He pushed through some swing doors, following the directions he'd been given. The hospital was massive but still a makeshift affair, bolted together from foundation plates and scavenged habitations and anything else that would form walls and floor and ceiling.

He realised with a start that he was happy. Not jubilant, but more positive than he'd felt in months, despite the smell and the lingering effects of the radiation. They were out of danger, they'd survived, and they were still together.

And more than that, he felt that he'd made progress with Donnie. Not amazing progress, and there was still so much residual tension there, but he felt that maybe, if he could sit him down and just hash it out, they might move forward. And Donnie was stuck in bed. What better place to sit down and just talk?

But when he finally found their room, only Raph was there, sitting up at least, but still looking grey. He was hooked up to an IV and didn't look happy about it.

"How are you feeling?"

"I'm fine. Ready to go. Tell them to unhook me from this damn thing." Leo knew him too well, knew that the grumbling was just Raph's way of dealing with anything medical. Leo sat on the bed next to him and patted his arm, knowing it would enrage him and take his focus off the hospital for a while. Raph snarled and thumped him, but it was a pathetic attempt compared to his usual strikes. He seemed to realise it, sinking back onto the pillows, his face paler than normal.

How was it that his knowledge of one brother was so complete, but his knowledge of another so patchy? He thought he knew Donatello. But Donnie was no longer the brother Leo thought he knew. "Where's Donnie?" Leo asked, expecting him to be nearby, getting his burns treated.

"Checked himself out."

"I thought they said a week at least."

"You know Don. Knows better than anyone else."

Leo couldn't tell at this point if Raph's remarks were because he was mad at Donnie, or just mad in general. "Do you know where he-"

Someone knocked, and Leo stood. Jacquie from the Salvation stuck her head around the door. "Hey guys. I was looking for Donnie."

"He's not here," snapped Raph.

Leo put a placating hand on Raph's arm. Jacquie was a friend. "He checked out."

"He did? I thought he was in for a while. Bought him his sign-up papers." She held out a thick envelope.

Leo stared at it. He knew intellectually what it was, but his heart wouldn't accept that it existed, that the envelope contained papers that would help Donnie to walk away from them. That he had already arranged to walk away.

How long? How long had he been planning to leave them?

"Uh, I can give them to him myself, I guess," said Jacquie, withdrawing the envelope.

"No, sorry, it's fine, I can pass them on." Leo took the envelope with fingers that shook. "Sorry, still a bit dopey." It was so weighty in his hand.

"Thanks Leo. Really thanks. I can't tell you how much this means to us. We need a medical technician badly. Half of my arsenal is in for repair, and if we can do repairs out on the line, it will make things so much easier. We never thought Donnie would leave you guys. I'm just- We're so excited to have him. Thanks so much."

Leo managed to stammer something, but his head was buzzing. Raph on the bed glowered like an enraged hornet.

Jacquie looked from one to the other of them, as if suddenly realising that her delight wasn't shared. "Well, thanks again," she said, backing away. "I'll see you guys around."

When she was gone, Leo stared at the envelope, the white paper, the mark of the Salvation in the corner.

"Drop it in the trash. Pretend you never got it," said Raph savagely. He reached for it.

"No." Leo pulled it out of his reach, tucked it under his arm. "We can't do that."

"Yes we can."

But he couldn't. He couldn't lie outright to Donnie about this. No matter how much it hurt.

"Leo. You can't let him go."

Leo shook his head and turned to the door. "I'll fix it," he said over his shoulder. "I'll-" But he didn't know if he could. He didn't have a plan.

During the long walk down to the hanger where the Honour's Blade was docked, he wondered if he should try to stop Donnie leaving. Maybe if Donnie had some space, maybe if they weren't snapping at each other every five minutes, things would settle down. Donnie might listen to him, if they escaped the cycle of attack and defend that had been their lives for months now.

But the thought of Donnie on another ship, away from them, out of reach of their help, should he need it, made Leo sick. And Raph wouldn't take it. Raph would blame him for letting Donnie go. He would replace one angry brother for another.

When he stepped into the hangar bay, flashes of light on the walls told him where Donnie was and what he was doing; repairing the hull. Leo took a deep breath, swallowed his fear and climbed the ladder up the side of the hull.

Donnie was at the top, face behind a face shield and Leo looked away as the welder flashed again. When the light died down he crossed the hull to Donnie, making no attempt to be quiet. Up close, Donnie was a mess. Hard black blisters covered his arm and the side of his face. Some of the ones on his arm had burst, and oozed blood and fluid.

"Hey," said Donnie, from behind his face shield.

"Shouldn't you be in the infirmary?"

Donnie shrugged, not turning to face Leo. Leo sighed. They were back to this again. Crisis over, the peace treaty had been revoked. Leo held out the envelope.

Donnie switched off the welder and extended his hand for the envelope. He didn't open it, just lay it in his lap.

"Jacquie dropped it off at the hospital." All the way down to the hanger, Leo had been reminding himself to go carefully, to work his way through this calmly, not to accuse Donnie of anything. But he found he was shaking. "How long have you been planning to leave?" The words burst from him, full of pain. His voice was uneven. "When were you going to tell us?"

Donnie flinched, and Leo was glad of it, glad someone else was hurting instead of just him. Then he felt guilty for wanting Donnie to hurt more than he already was.

Donnie didn't say a word, didn't raise his visor. He kept staring at the envelope in his lap.

Leo turned away, suddenly empty. What was the point of trying any more? Donnie had been walking away from them for months. From him. Well now it was Leo's turn.

Every step felt like he was tearing a piece of himself away.

"I don't think this is going to work anymore. Us."

Leo froze as Donnie's words reached him, soft and barely audible. What should he do? Keep walking, or turn back?

Both ways hurt. But habit was strong, so he turned around. Donnie had taken off his faceplate, but he was still staring at the envelope.

Leo gathered the last of his resources. "I don't want to lose you." He swallowed. But I feel like I already have. He couldn't say it. He was afraid that if he did, it might turn out to be true.

Donnie turned the envelope over in his hands. "I don't really want to go."

"Then why-" Leo couldn't say the words, so he gestured at the envelope. "Why?"

No answer came. He stood there in silence, looking down at his brother, at the weeping marks on his arm. "Please stay," he said. "Donnie. Please."

Donnie's breath came out in a harsh cry. "I can't. I can't do this anymore. I can't go through this every day."

Leo swallowed against the tight ache in his chest. "I would rather have you here and hating me, than somewhere else."

Donnie's voice was barely audible. "I don't hate you."

"You've been...acting like you do."

Donnie raised a hand to rub his face, winced and dropped it again.

"Donnie, if I could change things, I would. But I had to..I had to make a decision. If we'd let that Kraang scout go to help the Featherlight, then even more lives would have been compromised. I told myself we could make it back in time." He swallowed. "I was wrong."

"I know you needed to make that decision." Donnie's voice was sharp with pain. He swallowed visibly. "It's not you. It's not the Featherlight. It's us. I don't know what we've become."

Leo blinked, confused. "What do you mean?"

"What are we, Leo? What are we doing?"

"We're fighting the Kraang."

Donnie shuffled his shoulders.

Leo struggled to understand why he was upset. "We're at war, Donnie. We're helping keep people safe."

"Are we? Some days I wonder."

A light went on in Leo's head. "Is that why the Salvation? You wanted to help people?"

Donnie sighed. "Something like that." He looked up at Leo for the first time. "I can't forget, Leo. I can't get them out of my head."

Leo nodded, swallowed, nodded again. "I can't either." Leo forced himself to meet the brown gaze.

Donnie looked away. That was it, then. That was his last volley. He had nothing left. He closed his eyes, exhausted by the effort. It shouldn't be this hard, just to talk to his brother.

Something tore and his eyes flew open. Donnie ripped the envelope in two and stood.

Leo reached out, his vision blurry, and put a hand on Donnie's shoulder.

Donnie reached up and patted his hand. "All right," he said. "Let's...let's try again." He tossed the envelope halves into the trash.

Leo wiped his eyes hastily and followed Donnie down the ladder. It was a start.

Donnie looked up at him, not with a smile, but with an attempt at one. "We'd better rescue Raph before he tears out his IV and runs off."

"Will he be all right in the ship?"

"Yeah. I can manage his meds, and you can manage him." He paused. "That's what you're good at."

"Not always," said Leo.

They walked in silence for a while. "More than you think," said Donnie. He draped a long arm over Leo's shoulders. "Thanks," he said quietly.

It was enough.

Thank you so much for reading What Lurks in the Dark. I hope you enjoyed it!

If you're looking for more science fiction turtles, you might enjoy my story Turning Point.

Thanks again for reading, and please let me know what you think!