Raphael was getting familiar with being surrounded by the technical speak of the "brains", as he'd been lovingly referring to the docs and Donny. Today, however, he wasn't interested in listening to Chinese. They were getting ready to move forward with the first of the stem cell treatments for Michelangelo, and the red-masked turtle wanted to understand as much as possible. He didn't usually like asking many questions when Mike was sitting by too, but he was getting to the point where he simply didn't care.

Shell, I know Mike's got more questions than I do. Just 'cause we might not understand the answer is no reason not to ask.

Raphael turned as he felt his brother's gaze fix on him, pleading blue eyes giving him all the encouragement he needed.

"Caleb," Raphael called, breaking the man's staring contest with the microscope. "We need you to go over this again, slowly." He snuck a glance at Mike, and his younger brother nodded. "Walk it through from the beginning."

"We're going to be using a method of implantation that will involve directing the iPs cells into the lining of Mike's lungs, where oxygen is absorbed and carbon dioxide is excreted. The goal with the first treatment is to implant cells that will hopefully then transform into new lung tissue. The second wave we'll perform later will involve flooding the lungs with the iPs cells that have been cultured, with the goal of overpowering the mutated cells that are destroying tissue.

"On this first try we want to focus primarily on the lung tissue itself, and begin regenerating portions. This will also be the true test of the iPs cell's ability to adapt, and the receptor blocker's success rate in teaching the immune system to ignore them. The second part of the stem cell treatment is going to need to wait a few more weeks," Caleb finished.

"Why do you have to wait?" Mike asked.

"First of all, because I want to give those iPs cells more time to mature, and the specialized equipment will bring them up to speed quicker than the natural environment of the lungs. Secondly…because the 'free form' cells are where the most risk for rejection lies."

"What happens if my body does reject them?" Mike wanted to know.

"That's a case where a lot of different scenarios are possible. I've explained to you that none of these methods have been tested on humans, let alone someone with your special biology. The main risk of the immune system rejecting the iPs's shouldn't be a factor, but if the manipulated stem cells aren't stable enough to hold their own against the mutated ones, it could end up making you sicker."

"What's the worst thing that could happen?" Mike pressed.

Part of Raphael wanted to cover his ears and not listen to what was coming next, but if his little brother could live with the knowledge, so would he.

"There could be additional respiratory problems, pulmonary distress, shock...basically a number of conditions that would spell bad news," Caleb said carefully. "Which is why we're proceeding slowly. I don't want to call this strictly a trial run, but that's kind of what it is. If we're successful at integrating the iPs's into new lung tissue, then we'll move on to the second phase of the transplant."

"And rejection doesn't always happen immediately, right?" Mike clarified. "It can take days or weeks, even months. I thought that was what Doc said."

The man nodded. "That's another reason we want to allow a delay between treatments. If all goes well on this one, then the following treatment will possess both halves of the solution. We'll implant additional iPs's into the lining of the lungs to continue the new tissue trend, and we'll release the flood to fight the mutated cells. The most promising thing about this therapy is that the naturally occurring cells within the lungs don't reproduce readily. That means there are a limited number of these 'rogue' cells, and in theory we can keep pounding the lungs with the healthy kind until good triumphs over evil. You guys are familiar with the concept."

Raphael nodded. "What's the actual transplant gonna involve? You've probably already told Mikey, but I'm curious too."

"It's administered intravenously, and it should be completely painless."

"So if it goes well, nothing's gonna hurt him?"

"There is always the risk of side effects and complications. We're going to keep your brother under close observation to make sure he isn't developing anything like that."

"And you need to keep taking healthy cells from me too?" Raph asked.

"For the next couple of weeks, yes, while we're still growing new cultures."

The red-masked turtle shot Michelangelo a grin. "Who'd have thought I'd be the one to save your shell?"

"I knew this was gonna go to your head," Mike complained. "Beck's waiting for me downstairs. Is it okay if I take off?"

Caleb nodded. "As long as you don't literally take off."

The orange-masked turtle chuckled. "Dude, you have no idea how close to the truth you are."

Donatello noticed Mike getting up from where he was sitting, and he joined the youngest turtle as he left the room.

"I don't need anything else from you right now either, Raphael. We can get you out of here too," Caleb told him.

He hesitated, glancing toward the door and then back at Caleb. "I don't know that I'm ready to go yet."

"If you have other questions, now's a good time to ask," the man replied.

Raphael shook his head. "This whole thing is just weird to me. How'd I end up being the best match for making these iPs cells? Are you sure Mikey's system is gonna accept mine? I'm really worried about the bottom dropping out and him getting worse."

"Your fears are founded, Raphael. This goes against the natural order of DNA. But if it makes you feel any better, you're already defying the laws of nature by existing. Biology teaches us that mutations are harmful in almost every single case, with a margin for success that's so small it's hardly conceivable. Yet here you are, living, breathing, and defiantly healthy against incredible odds."

"We're not all healthy," Raphael pointed out. "Our Sensei is gone, and Mike would be out the door without you too."

"And yet, how many years went by without complications?"

"I guess that's true, but it sure doesn't mean much now," Raph said bitterly.

Caleb took a deep breath. "I understand that it's discouraging. But the good news is, there's still hope, Raphael."

The red-masked turtle looked at the man seriously. "Why me? What's so special about my cells, Caleb?"

The doctor shifted awkwardly, and looked over his shoulder at Luke and Marcus. "It's a matter of several factors."

Raphael's gaze hardened. "What aren't you telling me? I know there's something."

"I don't know if...um..." Caleb's discomfort was obvious.

"I know I sound a little like a hot head sometimes, but I'm really not that bad with my friends. What are you not supposed to tell me?"

Surprise registered in Caleb's eyes before he swallowed to contain it. "It isn't that I'm not allowed to say it; I'm just not sure if I should be the one doing this."

"We're all relying on you now, aren't we? Even if it's bad, I need to hear it. With me it's like pulling off a band-aid: I'd rather do it quick."

Caleb smiled. "I never liked doing it that way, but I'll do my best. Out of all four of you, your cells are the healthiest."

Raphael cocked his head. "What do you mean the healthiest? Is something wrong with Leo and Donny?"

Caleb scooted his chair closer to the bed Raphael was propped up in, filling up the space he'd created between them. "You know that we took several samples from all of you, including cells from the lungs. In your brothers' cases we found more of the cells possessing the abnormality that causes them to eventually mutate spontaneously."

"Are you telling me they're sick too?" he whispered fiercely.

"No, that isn't what I'm saying. The abnormality still appears to be in an early stage, meaning it could be years before the condition became acute in them the way it did with your father and Michelangelo."

"But Donny said that all of us have this thing. How could I be the only one to luck out?"

"You have the abnormal gene too, Raphael, but your cells contained the lowest occurrence of them. That's why we consider them the healthiest."

Raphael was silent for several seconds. "Do Don and Leo know?"

He nodded.

"What about everyone else?"

"That's at their discretion, Raphael. I'm sure it was all going to come out, it was simply a matter of timing. I don't think your brothers wanted to fuel any further discouragement."

The red-masked turtle braced a hand against his forehead, closing his eyes as new fear overtook him. Finally, he looked at Caleb again. "Do you think this is going to work?"

The older man held his eye contact, but didn't speak right away. "In theory," he said at last. "I want to give you some certainty, Raphael, but I can't. The only thing I can assure you of is that we're doing everything we can."

Raphael took a shuddering breath. "Have you...do you know if...I mean, we gotta know what we're up against, right? I could talk to Karina. Olivia should probably get tested too."

Caleb nodded slowly. "It would be in her best interest. I don't know that I should have told you all of that, but I hope you understand your brothers weren't trying to hide anything from you."

That ain't what it feels like, he thought inwardly.

"I'm sorry. I know this is difficult to hear," Caleb said quietly.

Raphael focused on the man once more. "Don't apologize to me, Caleb. We're the ones who've been making this harder than it should have been, and I'm the worst offender. We're all pretty protective when it comes to Liv, but that's not a good enough excuse.

"You proved that you were trustworthy before you ever stepped foot on this mountain, but I couldn't let that be good enough. It's just being this helpless…I don't know. I think part of me had a harder time with trusting you because I couldn't keep anyone safe on my own. I'm sorry. I hope you realize we're all on board with you now. I appreciate you being honest with me, I really do." The red-masked turtle extended a hand toward him, and the man accepted it.

Caleb gave him a small smile. "It feels good to hear, Raphael."

The red-masked turtle was quiet for the remaining portion of the day. Extra pain meds had been offered; he suspected because the docs assumed his silence equaled suffering. He didn't want them. Raphael wanted to be left alone to process things. He did his best not to be cold toward Karina, while making it clear that he wanted a little space. But when Leonardo came to him shortly after the dinner that he couldn't stomach, he was actually relieved.

"Raph?" His brother's tone was tense, as if he half-expected Raphael to bite his head off for approaching him. "What's going on?"

"You should have told me," he replied shortly.

"Told you what?"

"I talked to Caleb today. He was honest with me, more honest than you guys have been," he said sullenly. Raphael was seriously frustrated with his lack of mobility. He wanted to pace or run, but he couldn't do anything but sit there. "He told me about why they're using my cells."

"Raph, Don and I aren't sick," Leo said.

"But you're gonna be, aren't you? We're all like some freakin' time bomb waiting to explode. Did you tell anybody? Do your girls know?"

"I spoke with Calley, but I don't know if Don told Jen."

"Why the shell didn't you tell me?"

"Is this such a big mystery, Raph? Aren't we dealing with enough as it is, without chasing down more things to worry about? We're not having issues yet."

"You even added the 'yet'," Raphael countered.

"Please don't be angry. We weren't going to keep it from you, and we didn't tell the docs to hide it either. Don and I didn't want to dump this on everyone at once. You understand that, don't you?"

"I'm not everyone!" he said sharply. "I'm your brother."

"Yes, you are," Leo said softly. "I'm sorry. It was going to come out soon. Put yourself in my position, Raph. Do you want to be the one to head up that family meeting?"

"Promise me that you're not hiding anything else."

"We're not, Raph. Please believe me. We didn't want to add to the existing burden."

"I get that, Leo, but I shouldn't have had to hear it from Caleb."

The blue-masked turtle shook his head. "I'm sorry, Bro," he repeated, dropping to his knees by the bed. "Is this why you've been down today?"

"How was I supposed to act? Should I have been happy, relieved? No, when someone tells you that your brothers' days are numbered, I think you're allowed to get upset."

Leonardo nodded mutely.

"I guess...maybe retreating isn't the right thing to do though," Raphael said evenly. "What with Mikey getting the first treatment tomorrow. We ought to be together, huh?"

"I think it would be better," Leonardo said. "Are you up to it?"

Raphael nodded. "Yeah, I s'pose. We're nothing if we're not a family, right?"

Leonardo smiled faintly. "That's one way of saying it."

The red-masked turtle let out a tremendous sigh. "You wanna help me get out of this room?"

"Sure, Raph."

"Aren't you getting tired of hauling my shell around yet?"

Leo waved him off. "You'd do the same for us."

"Yeah, but I probably wouldn't be as nice as you guys."

Leonardo laughed. "That's probably true. I'll call Don to give me a hand. We're not getting sick of helping you, Raph. If we can't be there for each other, we've got no business calling ourselves brothers."