Archive of Our Own ^beta

Chapter Text

Splinter did not remember his days before the lab.

The mutagen that had been injected into him had given him a consciousness that he had not had as a simple rat. He had thoughts, emotions, curiosities, feelings that once had not existed within him.

He watched as the small human girl interacted with the larger human man, and marveled at the kindness they showed each other. There was love between the two, and Splinter was in awe at the fullness of joy that was evident on their faces.

He had wondered what it would be like to feel the same, and then he saw the four little turtles brought into the enclosure beside him.

Leonardo, Raphael, Donatello, and Michelangelo.

They were small, wonderful, and perfect.

When April had rescued them, Splinter was grateful. Not only because she had rescued him from certain death, but also because she had given him the opportunity to be a father to the boys.

As he watched them grow up, Splinter felt as though his heart could not have gotten more fuller and happier. His four sons were talented, bright children, and being able to teach them gave Splinter the purpose he had been searching for. When they grew taller and stronger, Splinter worried for them, wanting his boys to be safe and unharmed. He knew, however, that their curiosity would get the better of them, and he would not always be able to keep them in their happy little home beneath the streets of the city.

Splinter’s fears were quickly outweighed by the pride he felt for his sons as they saved the city not once, but twice, from the Shredder, working with the humans to stop him and his alien allies. He could not help but feel overcome with emotion. His boys had been through so much, and deserved to be celebrated as heroes.

With his sons, Casey, and April, Splinter truly believed his life was full, and that he needed nothing else in his life.

He was content.

Then, three more groups of his sons had fallen into his life (quite literally), and Splinter was completely and utterly thrown off-balance.

Two of the groups were happy, bubbly versions of his sons. Splinter was almost emotional watching them, reminded so very much of his boys when they were children. Their innocence and joy made his heart fill near to bursting, and Splinter wanted nothing more than to sit and listen to their babbling stories.

The third group, however, worried Splinter more than he would admit.

They were quiet, and stuck to each other’s side like glue. The humans that accompanied them, when they first met, had formed a protective line behind them, staring down the others as if they were going to hurt their turtles.

The guarded, almost worried look in their eyes had broken Splinter’s heart, and when he heard of what their teacher had done in their dimension, the anger that filled him was unlike anything else.

As they all got to know one another, Splinter watched the group of guarded boys slowly let their walls down. He was delighted to see them joke around with their brothers, relaxing and joining in on afternoons in the various lairs, movie nights, and quiet patrols.

Even more so, Splinter’s heart warmed as the boys became more comfortable around the three versions of Splinter. Raph was first, of course, but his brothers followed, gravitating towards their different senseis. They began opening up, talking about their own training and journey with their weapons. They stiffened less around them, their eyes losing the pained look when talking to them. It was bittersweet to Splinter, as he knew why they reacted in such a way, and hated that they had been so fearful of a simple conversation at first.

The first time that Leo had approached him, completely on his own, Splinter was sitting in the dojo of his home, preparing for one of his sessions with Leonardo. The arrival of the younger version of his eldest son had been surprising, as it was still very rare for the boys to be without each other in the different dimensions.

“Good morning, Master Splinter.” Leo said, entering the dojo with a shy look on his face.

Splinter smiled warmly at him, setting down the teapot on the small table in front of him. “Good morning, Leo.” The boy came closer, kneeling in front of him, staring down at his hands. “How are you?”

Leo started at the question, like he was not expecting to talk about his well-being. “I’m managing.”

“Would you like to talk?” Splinter asked gently. He did not want to prod, but he wanted the brothers to be able to talk comfortably. “The boys know not to come into the dojo while meditation is happening, so you can talk freely.”

It was a rule that had been put in place as the boys were growing up, after one too many instances of Raphael chasing Michelangelo around, or Donatello bursting in with a new invention.

“What was it like?” Leo finally asked after sitting silently for a few minutes, a conflicted look in his eyes.

Splinter tilted his head slightly. “What was what like, my son?”

Leo kept his eyes on his hands, playing with a bracelet on his wrist. “Not being human. Just being… a rat.” His face closed off, calm replacing the flash of hurt. “Hamato Yoshi started off as a human, and that was always something he wanted to be again. He originally bought us as pets and only took us as his sons after he was mutated.”

The day that Splinter met Hamato Yoshi, he would smack the man with his tail so hard that he would fly into a wall. The hesitation on the child’s face in front of him pained Splinter’s heart, and he hated that there had once been a time when Leo would ask questions happily and without having to worry about being scolded, a time that was long gone.

“I gained a human consciousness after being injected with the mutagen. While I have always been a rat, I have also always loved my sons as a human would love their own children.” Splinter explained, keeping his voice gentle. “When we met April again, I told her that I had vowed to love the boys as her father had loved her.”

“But you never wanted to be a human?” Leo asked, almost desperately as he looked at Splinter.

He reached out, placing a hand on the turtle’s arm. “No. I am happy with how I am.”

Leo’s shoulders sagged, and he shifted from being on his knees to sitting in a criss-cross position. He rested his chin on his hands. “I’m still trying to wrap my head around everything that happened.”

“Would you like to walk through it?” Splinter asked, pouring Leo a cup of tea and placing it in front of him.

“I just… he picked me to be the leader of my brothers because he trusted me. He trusted my judgement and that I would be able to have a level head.” Leo began, not drinking the tea but holding the warm cup in his hands. He looked down at the liquid, studying it. He still spoke tentatively, as though worried about upsetting Splinter. “I didn’t even realize what was happening until I noticed Raph reacting. I wanted to keep the peace, and in doing so, I think I hurt my brothers more.” Here, Leo paused to take a sip, and something twisted in his face. The guarded expression faded, and his eyes filled with tears as he took a second sip of tea, taking a deep breath before continuing to speak. “He chose me, but I can’t even trust him anymore because of what’s happened, and I’ve been second-guessing what that means for me. I’ve put so much of myself into who I am as a leader. Who he turned me into.”

His voice broke slightly, and Splinter could see right through the boy. “You worry that you will become like him.”

Leo nodded, placing the cup on the table. “I’m the reason Karai came back into our lives. I met her, and I brought her back to the lair.” He glanced at the entrance of the dojo, where Splinter could just barely make out the sounds of multiple voices as the brothers outside talked and laughed with each other. “I love my brothers so much, and I don’t want to hurt them again.”

“You did not hurt them, Leo.” Splinter said calmly. “You have a kind heart, my son, and your family is your rock, your life. You have done so much for them, and you wanted to do something for your father.” Splinter hated even calling the man that word. He did not deserve that position, not after what he had done to the four wonderful boys he now saw as more sons. “You cannot look into the future. You did not know who Karai was when you met.”

A weight seemed to lift off of Leo’s shoulders, and he looked lighter. His shoulders sagged slightly, and he picked up his cup again, drinking slowly.

“How did you pick Leonardo to lead the group?” he asked after finishing off his tea.

Splinter chuckled quietly, refilling both of their cups. “The boys deferred to him during training when they were young.” He remembered the time training his sons, how they grew and matured, finding their own positions in their team. “They are all the same age, but their personalities are all so different. Leonardo and Raphael butted heads at first, but in the end, Raphael was the one who told me to make Leonardo the leader.” Splinter remembered the evening his second-oldest had approached him, asking if they could talk. He had not been surprised in the slightest when Raphael had all but demanded that his father make Leonardo their leader. When he found out, Leonardo had promptly told Raphael that he would be his second in command, and Splinter had just smiled at the interaction. “You and Leonardo are so similar, my son. You both think so far ahead into the future, imagining the worst possible situation that can happen. That can be a blessing, but it is also a curse.”

“Raph tells me I overthink things sometimes.” Leo said with a grin, obviously not offended by his twin’s statement.

“I imagine he does.” Splinter chuckled. He sobered, however, looking intently at his son. “Overthinking leads to spiraling, and the belief that things are your fault when they are very much not. What Hamato Yoshi did is on him, and it is in no way your fault, my son. You were trying to be a kind son, and he twisted that.”

Leo looked less pained, and more thoughtful after listening to what Splinter said, and his following question was not one fueled by sadness, but curiosity. “If you and your sons had the chance to be human, would you take it?”

Splinter thought for a moment. He thought of the life he had with his sons, their lair, their oasis beneath the city. He thought of them growing up and being able to have lives that he never imagined they’d experience. He looked back at Leo with a firm shake of his head. “I would not.” Leo leaned forward, curiosity making his eyes wide. “My sons have already gone through that choice, and it nearly tore them apart. In the end, they decided not to take it. I have never known what it is like to be human.” He had occasionally wondered, but Splinter had never felt the pull to be human. He was content with his life. “The boys have human friends, and they have the trust and respect of the human police after working with them to fight the Shredder. I believe there are even some humans who know of their existence outside of the ones I know of.”

Particularly, the human siblings that Leonardo and Raphael had been not-so-subtly visiting every week or so, but Splinter would not open that can or worms. He was patient to wait until his sons’ approached him with their very obvious crushes and go from there.

“I haven’t told my brothers this,” Leo began, dropping his voice to a quieter tone as though his brothers could hear through the walls of the dojo, “but sometimes I wonder what would have happened if he had never taken us from the pet store.” Splinter stayed quiet, letting the boy talk his thoughts through as they came to him. “Like, would we have stayed together? Would someone have bought us for their kids? Would we have been bought for an experiment, like the others were?” Leo took a deep breath, placing his arms on his knees and leaning forward. “I love being with my brothers, and being with April, Casey, Xever, and Chris, but I can’t stop feeling hurt and sad whenever I think about our days growing up.”

Splinter hummed quietly, acknowledging Leo’s words as he looked back up. He had wondered, once, many years ago, what his life might have looked like if Sacks had never set the fire in the lab, or if they had only kept him and never brought in the four baby turtles that changed his life for the better.

“There are days that I think about what happened in the lab. For the most part, we were treated well.” Splinter began. “Occasionally, however, Sacks did not always treat us with the same gentleness that April and her father did. Those days that I think about are painful memories.”

Leo looked almost desperate as he rested his hands on the table. “How do you still think about those days, then? Without being upset?”

Splinter reached out, taking one of Leo’s hands in his. “I remember the good.” He smiled, all the memories of his sons' training, laughing, and joking together coming to the forefront of his mind. “I remember watching April with the boys, and how they received so much love from her. I remember that those days are what led me to where I am now, with the sons I watched grow, and more sons to love, and other rats I now see as my own brothers.”

“Growing up, Raph was actually the one who found Space Heroes.” Leo reminisced quietly. He had mentioned to the others his love for the comic and television show, and it had amused everyone how quickly he had gotten on with Blue, who immediately began comparing it to Jupiter Jim. “He thought I’d enjoy it, so he found me some comics people had thrown away, and gave them to me.” Leo’s smile grew, and Splinter cherished the sight. “He jokes about hating it, but I know he will watch it if I ask because of how much it means to me.” Leo grew quiet again, and when he continued speaking, there was a more melancholic tone to his voice. “So many of our childhood memories have Hamato Yoshi in them.”

“So look back on them with joy, Leo.” Splinter said, squeezing his son’s hand tightly as if he could push the positive memories forward, and steal every painful memory from him. “The good memories are good. You do not need to feel guilty to remember those times in your life.”

Leo opened his mouth, closed it as if he was second-guessing his words, and then he spoke. His admission was quiet, as though he was ashamed. “I miss him. I miss who he was, how he treated us.”

Splinter sighed, sad and quiet. “You can miss him, my son.” Leo looked at him with surprised eyes. “But also, know that you have more fathers now who want to show you that same love and care that he once did.”

“That helps the hurt.” Leo said, sitting up straighter as something healed in his eyes. He looked around, taking in the dojo they sat in with a fond look. “He used to meditate with me. I loved doing that. It helped to center me, and it was something that kept me from overthinking.”

“I do the same with Leonardo.” Splinter said, and he reached for the teapot. “Would you like to meditate together, Leo?”

Leo beamed, open and soft. “Yes, please, Father.”

Leonardo joined them a few minutes later, entering the dojo and placing his weapons to the side. He sat beside Leo, nudging his younger brother’s shoulder playfully and making the boy roll his eyes in mock annoyance.

Splinter’s heart warmed at his sons’ interaction, and he closed his eyes, breathing deeply, and comforted by the knowledge that, no matter which ones they were, his sons would be safe and content in his presence for as long as he lived.

Chapter Text

Splinter knew that his relationship with his sons had gone through ups and downs.

He knew that there were times he was not the best father he could have been, but he and his boys had grown together, and their relationship was stronger than ever, especially after fighting against the Kraang.

Now, however, there was a new group of sons to grow with.

Splinter had seen their reactions when they had all first met.

There had been openness, warmth towards the others, a genuine excitement after the first few meetings. When it came to Splinter and his boys, there seemed to be another level of difficulty with connection.

Leo, Raph, Donnie, and Mikey had heard the story of how Splinter found his sons, of his human life prior to mutation, and had almost immediately tensed. They listened as Blue told them excitedly about meeting Cassandra, then Karai, and getting to know them. The others had not noticed, but Splinter had seen the glimpse of sadness, and the flicker of envy on the faces of the boys.

It was not until he heard the whole story from them that he understood. Listening to the four brothers talk about their dimension, about their father who had once been human, it all made sense to Splinter.

Slowly but surely, the wall between the two groups fell, and all four quartets were getting along like they had known each other their entire lives. Splinter, in turn, found himself being trusted by the boys, and being pulled into more discussions as the weeks passed.

He was happy with the progress, happy to know that his own past no longer affected his relationship with the boys who now viewed him as a father.

On one of the occasions that they all visited Leo, Raph, Donnie, and Mikey’s new lair, completely taking over the smaller space and filling it with laughter, Splinter found himself roaming about the rooms until he made his way gingerly into the lab.

He looked around, impressed and slightly amused at the various inventions and technology that were scattered around haphazardly. Donnie sat at a large table in the center of the lab, hunched over and focusing intently on a set of vials, a computer, and a microscope that sat in front of him. He saw the turtle look out of the corner of his eye.

“Hey, Papa Lou.” Donnie greeted, taking his attention away from his work to grin at Splinter happily.

Splinter returned the smile, sitting on the other stool at the table. “Hello, Donnie.” He looked down at the items scattered on the table, and the scribbled notes on the whiteboard behind them. “What are you working on?”

Donnie looked back at the vials, picking one up to place inside the centrifuge. “Chris mentioned a few side effects of the retro-mutagen I made for him and Xever, so I’ve been working on a new batch to compare.” He pulled out another vial, this one glowing orange, and he carefully placed it on top of the table. “It’s not wearing off, but his canines are sharper than ever, and Xever’s able to hold his breath for long periods of time under water, longer than any human should, so I’m thinking that the first batch left them with some characteristics.”

Splinter was once again extremely impressed by the boy’s intelligence, and his ability to create a reverse version of the very thing that had transformed him and his brothers.

“Who is this batch for?” he asked.

“I don’t know. Anyone we meet who wants to turn back?” Donnie shrugged, turning off the centrifuge for the moment while they talked. “I like having some on hand, just in case.”

Splinter hummed. “That is very smart.”

Donnie looked at him hesitantly, his hand resting on the tube of retro-mutagen. His gaze flicked between the two focuses of his attention, and he spoke in a quieter voice. “Do… do you want any?”

“No, thank you, Donnie. I am happy with how I am.” Splinter said with a small chuckle.

“Really?” Donnie’s voice was full of shock. He almost immediately backtracked, shoulders hunching forward as he drew back. “I mean, it’s just…”

Splinter studied his son’s reaction, narrowing his eyes slightly as he leaned forward. “The other version of Splinter that you knew, did he jump at the chance to return to his human state?”

“Yeah.”

“Will you mind if I am completely honest with you, Donnie?”

Donnie’s face brightened, and he placed his elbows on the table, resting his chin in his hands. “I’d prefer that, actually.”

“Good.” Splinter said, settling into his seat. This had been a conversation he had been hoping to have at one point. He paused briefly, thinking over the words he wanted to say before actually saying them. “Your Splinter always had a tether to his human side. Whether that was with the Shredder, or his wife and daughter. There was always a part of him that yearned to become human, and when his wife and daughter returned to his life, that part of his heart did not hesitate.” Donnie nodded, listening intently as Splinter spoke. “Any pull I had to my human life has long since disappeared. There were moments, when I was first mutated, that I wished my life had taken a different path, but as I grew older, my responsibility lay with my sons. The humans of the Hamato Clan are gone. Any human attachments I have are gone, whether through death or by my own decisions. The boys were my sons the moment they were mutated.”

“So you stuck with them because they were a responsibility?” Donnie asked, almost accusingly. Splinter went quiet for a moment, looking at him, and noting the hesitance behind his accusation, the worry for his new group of little brothers.

He picked his next words carefully, knowing that sugarcoating things would not work. He had a similar conversation with his own four boys just before the Kraang had arrived, so it was a conversation he had been prepared for. “At first, yes. I stayed with the boys because they were babies and had no one except for me. I knew I needed to protect them from Draxum and Big Mama, and anyone else who would want to hurt them.” Donnie cracked a small smile at the mention of Draxum, and Splinter shook his head in amusement, knowing how the young genius and his brothers were surprisingly attached to the former villain. Draxum had been a surprising addition to their ragtag family. “As time went on, however, I did truly come to love the boys as a father. It took some time, but now I cannot, and I do not, want to imagine my life without them in it.”

Donnie looked down at his work contemplatively. “We were originally bought as pets, you know. We weren’t supposed to be his kids, or anything like that.” A heavy sigh left him, and his head dropped onto the table. “I know he loved us. It wouldn’t hurt so much if he didn’t love us for eighteen years.”

“I think he did, Donnie. He still does care but I believe his sense of importance has been unbalanced.” Splinter said, reaching out to rest a hand on his shoulder comfortingly.

“I asked him why, when I started making the retro-mutagen.” Donnie explained, voice slightly muffled from where his face was pressed against the metal of his lab table. “Why he needed it, why being human was so important.”

Splinter moved closer, keeping his hand on Donnie’s shoulder to encourage him to speak. “What did he say?”

“He didn’t really say anything about why he needed it, at first.” The story began quietly, the tone of voice a whisper as Splinter listened. “He made it sound like Tang Shen and Karai would be more comfortable, which I actually understood. Karai’s mutation was against her will, and I don’t even know how Tang Shen got mutated. So really, it was fine.”

“You wanted to help them as you helped your friends.” Splinter realized.

Donnie looked up, keeping his head resting on his arm as he twisted to look at his father. “Exactly. Plus, with April’s dad, I’d seen what it meant to people who had been mutated against their will.” His eyes went to the orange liquid lying on the table. “So making it for the two of them, it made sense.”

“When did Hamato Yoshi tell you it was for him as well?”

A quiet beat. “Probably a few weeks before Raph finally lost his cool.” Donnie remembered, tapping his fingers. “I was working in the lab, and he stopped in, and asked me how things were going. While we were talking, he sat down and told me that he had been wondering if I would be able to make one more dose for him.” He straightened up, stretching his arms above his head while he spoke. His tone did not sound bitter or resentful, simply as though he was remembering something casual that had happened to him. “I don’t know if he was planning on telling the others, but I told the other three as soon as I was done for the day.” Splinter was not surprised by that. He knew from his own boys that it was near impossible for any version of the four brothers to not tell each other every single thing that happened to them. It was something he loved and admired about all of his sons. “I genuinely think he had good intentions about it. I think he was trying to have the best of both worlds, but him wanting to be human… that told us where his priorities were.”

Splinter’s heart broke for Donnie, thinking about how hopeful he must have been. “Do you think he would have tried to keep up both ends?”

“Absolutely.” Donnie said, voice firm as he looked at Splinter. “Him being human, though, it would have changed things.” His gaze returned to the items on the table, and his hand reached out, rolling one of the empty smaller vials between his fingers. “I still love him. He still was our dad for eighteen years, as messed up as it got at the end.”

“You are not as angry as your brothers are?” Splinter asked gently.

Donnie laughed, a slightly bitter, almost disbelieving sound. “Oh, I’m still pissed.” His hazel eyes were bright with a brief flash of anger. “I think it’s because I somehow ended up spending the most time with him during those last few months we got. I actually saw the rationalization and his side more than my brothers did. It doesn’t make things right, but it makes the anger less all-consuming for me.”

Splinter was relieved, at least, that Donnie felt something. He was happy that the boy did not just write off what Hamato Yoshi had done, and instead acknowledged that it was messed up. “Do you regret it?”

“Making the retro-mutagen for them?” Donnie clarified, and Splinter nodded. “Surprisingly, no.” He looked to the entrance of the lab, as though making sure no one was listening. “I know I see things differently than my brothers. I look at things from a more analytical standpoint, and it honestly wasn’t much of a surprise when he asked about himself becoming human. It hurt, of course it did, because I was still holding onto hope that he’d at least make more of an attempt to think of how his decision would affect us.”

Splinter’s heart swelled with pride and affection for his son. “Is that why you and your brothers were hesitant about connecting with my sons and I?” Donnie’s determined face immediately dropped, and a guilty expression appeared as he refused to meet Splinter’s eyes. “I did notice, you know. I don’t hold it against you four at all.”

Donnie sighed. “It was really a mix of things.” He smiled sadly. “You’re the other Splinter who was once a human, and seeing you stick around for your sons brought up a lot of emotions. Plus, you guys have a Karai, even if she’s a ghost, who wants to help and be a part of your family.” His fingers resumed tapping on the table. “Cassandra is also kind of who we all had hoped Karai would be like.”

He could actually feel his heart shatter in his chest.

Splinter had felt a hunch about why the boys had taken so long, but the idea that they looked to Splinter’s family, and saw the one they may have been able to have? That hurt him, and he wanted nothing more than to draw every single one of his boys into his arms, and make up for lost time by telling them how much he loved each and every one of them.

“They are your family now as well. Karai and Cassandra.” Splinter decided to remind Donnie, his voice taking on a rare, gentle tone he only had when speaking with his boys. “They love you four as much as my boys, and I love you and your brothers as much as my own.”

“That helps.” Donnie admitted, smile growing as he moved to lean against Splinter, who happily wrapped an arm around one of his Purples. “Seeing you all, and seeing how much you care.”

Splinter rested his forehead against Donnie’s for a moment, and Donnie let out a contented sound. “Will you show me what you are working on?”

Donnie immediately perked up, eyes sparkling as he began diving into a detailed explanation of his experiments. “I took some blood samples from Chris and Xever, so now I’m looking at their DNA makeup to see where the retro-mutagen failed, and what got left behind.” He whirled around on his seat, pulling Splinter to follow after him as he pointed to the whiteboard. “They actually told me they don’t hate the side effects, so I’ll probably leave it, but I want to use this information just in case we ever have a need for a retro-mutagen again.”

Splinter simply listened, watching with a full heart as Donnie’s face lit up more and more, hands waving around as he talked animatedly. He was happy to sit, soaking in his son’s data points and ideas for analysis, understanding nothing but the importance of being there, and letting him speak.