Leo had known from the moment Donnie had come home from the hospital, the younger turtle was his. Of course, at such a young age, Leo hadn’t known then how his obsessive and possessive behavior would evolve to become. 

It had been cute at first, or so his parents had thought, how Leo had insisted on feeding Donnie almost every time, how he would even go as far as to wake up at one in the morning, just to make sure he was the one there when Donnie woke up. Though, times when their parents would take Donnie from him, Leo acted out, temper tantrums, breaking things, even going as far as to bite his mother once when she tried to take Donnie from him. 

Eventually, they had just let him do as he liked, leading Donnie around by the hand, ‘allowing’ him to have friends because friends and interactions with other people were important. 

By the time Leo had hit his early teens, Donnie couldn’t go anywhere without his brother following him, proclaiming he needed protection. 

There had been multiple arguments, Donnie just wanting to be left alone, wanting to have his own friends. This, of course, had led to the younger turtle having a ‘secret friend’, someone Leo didn’t find out about until Donnie was in high school, and Leo was just starting his first job. 

The seventeen-year-old Donnie was smiling as he came out of the school, looking far more happy and giddy than Leo could ever remember seeing him. There was a light blush on his cheeks and a shine in his eyes as he looked at the Alligator walking next to him. 

Leo grit his teeth, his hands clenching the steering wheel, a hiss escaping him. Donnie never looked at him like that, never once in their whole life. He twisted his hand on the wheel, the leather squeaking with how tightly Leo was gripping it. 

When the alligator leaned down and kissed Donnie’s cheek, Leo saw red, kicking the car door open and standing up, glaring at his brother, who had the audacity to blush more at the affection shown him. 

Donnie hadn't noticed Leo standing there, how could he when he only had eyes for the alligator next to him. Donnie reached up to gently touch the muscular arm, his fingers barely touching the scaled skin. 

“Donnie! I’m going to be late,” Leo said. He didn’t yell it really but he spoke loudly enough that his brother did hear him. And whether it was the tone in Leo’s voice or the way he was looking at him, it didn’t matter, Donnie recoiled from his brother, his hand tightening on the arm he had been holding. 

“Donatello?” the raspy voice of the alligator questioned. 

“It… okay, Leatherhead, that’s just my brother. I just… I didn’t know he was picking me up from school today,” Donnie said, cutting off any other questions his friend might have had. “I’ll see you tomorrow.” He smiled at the alligator, daring to lean up, returning the earlier kiss to the cheek, before he hurried down the steps, books clutched to his plastron as he got into the passenger side of the car. 

Leo stood there, still glaring at Leatherhead, even as Donnie buckled up and sat there, gripping his books and waiting for Leo to get in the car. 

Leo didn’t get into the car until Leatherhead had turned and started walking away. Sliding back into the driver seat, Leo slammed the door, forcing the car into first gear and speeding out of the parking spot at a much faster pace than was probably necessary. 

“Leo! Slow down!” Donnie cried out, his hand shooting up to press against the roof of the car as Leo took a sharp turn. 

“Who the fuck was that!?” Leo demanded through clenched teeth. 

“Who was who?” Donnie shot back, narrowing his eyes at his brother. 

Leo growled, taking another sharp turn, speeding up as he pulled onto the highway, heading in the opposite direction to home. 

“Where are we going?” Donnie asked, trying to keep up his anger at his brother, though he was starting to get worried and perhaps a little scared. 

“Who were you kissing, in front of the whole fucking school?!” Leo asked. 

“Why is that any of your business?” Donnie hissed back. “I’m getting really tired of all of this, Leo, constantly demanding to know where I’ve been, who I’ve been talking to, because honestly, it’s none of your business! You don’t OWN me!” Donnie snapped. 

“That’s what you think,” Leo said, his voice cold and possessive, much more so than anything Donnie had ever heard before, and it made his blood freeze in his veins. 

“Stop the car, let me out,” Donnie said. 

“We’re on the highway,” Leo stated. 

“Yes, I had realized that and I want out of this car, now,” Donnie demanded, looking around almost frantically, trying to calculate his chances of survival if he were to jump out of the car at that moment. 

He didn’t have long to think about it, as Leo sped across three lanes of traffic, nearly being hit by a truck, which sped past honking its horn, the driver no doubt flipping them off. 

The car did slow down as Leo rounded the corner, and Donnie tried to make a grab for the door then, only to earn himself an elbow in the nose. 

“Don’t you fucking dare,” Leo said. 

Donnie cried out, cupping his face, checking his fingers for blood, which thankfully there was none. The car came to an abrupt halt and Donnie looked up to see where they were, his fear only rising when he noticed that Leo had pulled them into a secluded wooded area. 

“You want out, there, get out. Walk your ass home,” Leo said. 

“Where are we?” Donnie asked, taking his phone out to try and find out their location, only to have Leo take it and smash it against the dashboard of the car. 

“No. Get out,” Leo said, leaning over Donnie and opening the car door. 

The cool air sent a shiver through Donnie and he looked out into the woods, the sun setting, hiding behind the trees, bringing the chilly night air with it. 

“You can’t be serious?” Donnie knew his voice was shaking, as were his hands as he stared into the dense forest Leo was trying to dump him in. A rough hand gripped his chin and forced him to look back into the sapphire-blue eyes, cold and possessive. 

“This is why you need me. You are helpless without me, Donnie,” Leo said. “All I’ve ever done is protect you, care for you. So, you are being given this one choice. Get out of the car now and I’ll never chase you down again, you can go live your own life, because it will prove that you can protect yourself, that you will be able to take care of yourself, and that I no longer have to worry about you,” Leo said. 

Donnie glanced out the window again, swallowing hard, but waited to hear what Leo’s other option was, because as it stood right now, he knew he wouldn’t make it home, or anywhere safe, before nightfall. 

“Or?” Donnie prompted when Leo said nothing. 

“Or you stay in the car and we go home, and by doing that, you acknowledge that you need me,” Leo said. 

Donnie thought that second option didn’t sound too bad, though he also knew his brother, knew there was a hidden motive there. 

Leo knew he had won the moment Donnie sighed, those reddish brown eyes closing in defeat, his brother nodding his head as much as the hand gripping his chin would allow. Leo had the sudden urge to kiss his brother then, to properly kiss him, pull him into his arms, and force his tongue into that mouth that had so often cursed at him. 

“Let’s go home,” Donnie said. 

Leo shook his head, blinking once and nodding. Lowering his hand from Donnie’s chin, he allowed his brother to close the car door before he started driving again, thankfully at a much more sensible speed this time. 

---------x

The following months passed slowly. It was once again rare to see Donnie without Leo anymore and Donnie was starting to truly fear his brother. 

Leo hadn't done anything out of the normal, but it was the look in his eye, the lingering touches, the gentle kiss on the cheek that felt like something far more than brotherly. 

The worst day for Donnie so far had been the final day of the school year and the start of summer vacation before he was supposed to go off to college. Leo had somehow discovered that Donnie had not only chosen a college on the other side of the country but was planning on moving there as well. 

This discovery had been nearly a week ago now and Donnie was waiting for the backlash from it. 

Each day after school when he got into the car, he expected his brother to drive him out to some remote spot in the woods and just keep him there. However, what Leo was doing was almost worse. Sitting in the car, the two turtles were silent as they drove home, where Leo would then lock himself in his room for hours and not speak to Donnie. 

The olive green turtle knew that Leo was upset with him, knew that he couldn’t leave with things so tense between the two of them. Because at the end of the day, Leo was still his brother and Donnie did love him, and he could clearly remember a time when he would have done anything for his older brother. 

Pulling up to the front of the house, Donnie watched as Leo parked the car before getting out, slamming the door shut, causing Donnie to flinch. Turning his head, he watched Leo make his way up the pathway and into the house. It was only when the older turtle was out of sight that Donnie got out of the car. 

Gripping his bag close to his chest Donnie followed Leo into the house. 

His heart was hammering in his chest as he saw the missing shoes and lack of suitcases in the hallway, indicating that his parents had already left on their week-long holiday, something they had been saving for, for a long time. Donnie knew they deserved the break and truly didn’t begrudge them the time off, he did, however, wish they had waited until after he had left for college. 

Letting out a sigh, Donnie closed the front door behind him and made his way further into the house, pausing when he saw Leo was sat in the living room for once and hadn’t gone straight to his room. 

“Leo…” he started. 

“I’m ordering pizza for dinner tonight, that okay with you?” Leo asked, looking at his brother, who nodded nervously. 

“Yeah, that’s fine,” Donnie said. “I’m just going to… um…” He motioned towards the stairs before making his way up to his bedroom, intending to put his bag away and change out of his school clothes. 

He looked over towards his desk, the acceptance letter to the college still sitting open there, his stack of new books sat neatly next to it and he couldn’t help but smile. He walked over and picked up the letter, wanting, needing to read it again, needing to know that it wasn’t a dream and that he was really going to do this. 

Donnie hadn’t noticed Leo coming into the room with him until he heard the click of the door and the snap of the lock, a feature Donnie had only added after Leo had threatened to leave him in the woods to make his way home alone. 

Spinning quickly, Donnie stared at his brother. 

“Uh… can I help you?” he asked, trying to sound more irritated than scared. 

Leo stared at him, that same cold, possessive look he had been giving him a lot recently. 

“Were you really going to just leave and not tell me?” Leo demanded. 

Donnie squared his shoulders. He had been expecting this, had been anticipating being cornered by his brother, had even mentally practiced what he was going to tell him when the moment finally arrived. 

However, Leo’s expression softened, looking more sad and forlorn than anything, and the harsh speech he had prepared slipped from his mind. 

“I… wasn’t sure how you were going to take it,” Donnie admitted. “You’ve not been acting like yourself recently and… I was scared.” 

“I never meant to frighten you, Don,” Leo said, stepping closer. 

Donnie felt his heart rate speed up. Even though Leo was looking at him gently, arms open slightly as if he were anticipating embracing his brother, there was something about it that had warning bells going off in Donnie’s mind. He held his hand up, pressing it against Leo’s chest when his brother got closer. 

“Well, you did, and you are,” Donnie said flatly. “I don’t know what changed but… something has, Leo, and I’m fairly sure it wasn’t me.”

“So, you moving away, you leaving me, is my fault?” Leo demanded, grabbing Don’s wrist and pushing it back, pinning it to the desk as he closed the space between them. 

Donnie yelped when he lost his balance and was tipped backward onto the desk, his new books and supplies scattering to the floor as he quickly struggled to stop Leo from pinning him fully. However, his brother was bigger and certainly stronger.

“You’re going to stand there and blame me for this?” Leo asked, his expression still soft and gentle, even as he used the full force of his body to keep Donnie pinned under him. 

“It is your fault!” Donnie insisted, bucking his hips to try and dislodge Leo from his person, clenching his eyes shut as he struggled harder. 

Then it happened, the slow grind of Leo’s hips against his own, the wet tongue licking a trail up his neck, all the way to his chin had Donnie freezing, eyes snapping open to stare at Leo. 

“I love you so much, Donnie, you are mine, you always have been,” Leo insisted, his hips grinding a little more firmly against Donnie. “I just want you to know how much I love you, you need to know that you belong to me.”

Donnie was stunned into silence, unable to move or fight back anymore. Mentally he knew he had to stop Leo, he couldn’t let his brother take things this far. if Leo did this, there would be no going back. 

“L-Leo…” Donnie started. 

Leo crushed his lips against Donnie’s, forcing his tongue into Donnie’s mouth as he continued moving his hips, his breathing picking up speed, and Donnie could feel the growing bulge his brother was rubbing against him. 

That was enough to snap Donnie out of it. Catching Leo off guard, he lifted his leg, managed to get it firmly between himself and Leo, and shoved him off. 

The older turtle crashed to the floor and Donnie quickly got off the desk, scurrying to the door, fumbling with the lock to try and open it. The door had just clicked open when Leo was against him again. 

“Shh," Leo whispered, using his body to pin Donnie against the door now, one hand around his neck, the other snaking down the front of his plastron, slipping into his pants. 

“Leo, stop, you can’t, Leo, stop!” Donnie pleaded, biting his lip when he felt Leo’s fingers slide along the slit where his cock was hidden, and to his embarrassment, he felt himself getting hard thanks to Leo’s ministrations. 

“You want this, as much as I do. Admit it,” Leo said, slowly rubbing himself against Donnie’s clothed tail. “You want me to touch you, you want me to kiss you, to fully own you,” Leo breathed. 

Donnie shook his head. “No, I don’t! You’re delusional!” However, even as he said this, he felt his cock drop down, his cheeks burning as Leo started touching him, playing his body as if he had done so for their whole lives. 

“If I’m delusional, then what’s this?” Leo asked, pressing his palm against Donnie’s cock, chuckling when Donnie’s hips twitched forward into his hand. 

“A-ah! An in-inevitable side effect of stimulation!” Donnie gasped out. 

“Wrong,” Leo said. “It’s your body telling you it craves my touches. You like me touching you, you always have,” Leo demanded. 

“H-have not! You… you’ve never-”

“Oh, but I have,” Leo breathed out, pressing his palm firmly against Donnie’s cock, causing the younger turtle to try and back up, only resulting in rubbing his tail against Leo’s own hard flesh. “I’ve had you begging for more, and today, I’m going to give you just that,” Leo said, suddenly grabbing Donnie and spinning him quickly. 

Confused and a little disoriented from the sudden movement, Donnie cried out as he was practically thrown onto the bed. He scurried to sit up but Leo was on top of him again, pressing his head into the mattress, his other hand grabbing the waistband of Donnie’s pants and ripping them down, exposing his tail and his ass. 

Donnie’s eyes widened and he kicked his legs, screaming when he heard the sound of a zipper and he felt the hard flesh slap against his asscheek, leaving a wet spot of precum there. His cries were muffled and he tried to fight back, terrified at what Leo was obviously planning, what his brother was doing to him. 

“Shh, Donnie, I’m not going to fuck you,” Leo said, leaning his body over Donnie's, his hard cock resting against Donnie’s bare ass now. “I wouldn’t hurt you like that.” Leo kissed Donnie’s neck. “Look at you, you’ve gotten so scared. I bet you’ve started to soften up.” Leo sighed, gripping Donnie’s hips, pulling them up so his ass and tail were sticking in the air. 

Leo shuffled and Donnie debated on kicking out again, of getting away. At least until he felt teeth on his tail. His eyes went wide and he turned his head as best he could to see Leo. 

He couldn’t see him properly but the wet tongue and teeth on his tail told him exactly what Leo was doing, and he knew, if he moved now, he would cause more harm to himself and most likely wouldn’t get away. He bit his lip, taking a deep breath and clenched his eyes shut. Leo had said he wasn’t going to… Donnie shook his head, unable to finish that thought, as it only brought him a small amount of comfort knowing he’d still be able to walk when Leo was done. 

The point was, he was stuck, and he had to let Leo finish what he planned and then go stay with Leatherhead for the remainder of the week. 

Donnie yelped when Leo’s hand gripped his cock a bit harder than he expected it to. 

“You can’t ignore me,” Leo insisted, stroking Donnie back to full hardness. 

Donnie clenched his eyes shut, he wanted to ignore Leo, he wanted to pretend that this was nothing more than a horrible dream, it was just some nightmare he would wake up from… Donnie’s thoughts trailed off once more, and his eyes snapped open once again. 

He had had dreams like this before, it was what had been fueling his growing fear of Leo. Being pinned down, touched, manipulated as his brother forced his body to completion. 

Leo had done this to him before! 

That thought alone had a sob escaping Donnie. Even though he couldn’t remember, even though he had thought they were just dreams, at the time, he was convinced now, from what Leo had said, and from the way his brother knew how to touch him, where to touch him, to get him so worked up so quickly. 

“Figured it out?” Leo asked, smiling as he ran his finger over the tip of Donnie’s cock, feeling the precum leaking from it. He gently lay his brother back down on the bed, using his legs to pin Donnie’s down. He gripped Donnie’s ass and nestled his cock between the soft mounds of flesh. 

Churring at the warmth surrounding him, Leo started moving, rocking Donnie’s hips into the bed, causing his brother’s cock to grind and rub against the blankets under him. 

“Don,” Leo breathed out. Moving so he was draped over his brother’s back, he kissed his cheek. “Told you… give you more,” he gasped out, moving his hips in long slow thrusts, his precum coating the space between Donnie’s ass cheeks, making his movements smoother, the tip of his cock brushing against Donnie’s tail in slow long strokes. 

Donnie was ashamed of himself when he felt his cock pulse with each slide of Leo’s and he bit his lip to stop himself from saying anything he would regret, because as much as he wanted Leo to finish and leave, he wasn’t about to ask his brother for more. 

“Let me hear you?” Leo requested. 

Donnie bit down on his lip harder, refusing to give his brother that much pleasure. Even as his breathing sped up, his cheeks burned, and his hips rocked forward on their own, his ass cheeks gripping Leo’s cock with each subtle move he attempted, he wasn’t going to ask for it, and he wouldn’t make any noise, not like this, and not for Leo. 

“I want to hear you, let me, please, Donnie,” Leo asked, his movements speeding up, grunting as he gripped Donnie’s hips, rutting against his brother, humping his ass as he got more worked up. 

Donnie silently begged for Leo to be done, he hoped that this was it, and then Leo would leave him alone. But Leo suddenly stopped, all friction stopped and Donnie gasped, his cock throbbing in protest, he turned his head to look at Leo. 

“You want it, don’t you?” Leo asked and Donnie shook his head. 

“No! I don’t!” he said, his voice strained with emotion, fear, anger, hurt, sadness. 

“You do want it,” Leo insisted. 

Donnie shook his head in protest again, not sure how he could explain to Leo that even though his body clearly wanted this, he didn’t. 

Leo pressed down on Donnie’s hips again, bringing a little more friction back and Donnie gasped, quickly turning his head away, not wanting to look at Leo. 

“I bet you’d make noise if it were Leatherhead,” Leo said. “I’ve watched you touching yourself in the shower, when you thought no one could hear you.” Another press on his hips and Donnie bit his lip hard enough to split it, trying to hold himself back from rocking his hips. “It would be so dangerous, sticking your cock into his mouth, all those teeth, but you like danger don’t you? Or is it, you want to wrap your mouth around his cock instead?”

Donnie felt like crying as Leo started playing with him mentally too, Donnie had imagined all those things, it made his blood boil and his cock throb. He couldn't stop the subtle movement, rocking his hips forward, feeling the wet patch on the bed under him from how much he was leaking. 

“I’m much better than him, I’ll give you everything you want,” Leo said, starting to move his own hips again, the cock sliding smoothly between Donnie’s ass, hitting his tail with each forward motion, causing the pleasure to spike just a little bit more. And now Donnie had the mental images of his crush in his mind too, every fantasy he’d ever had, and he couldn't help but notice now, the way Leo was pinning him, grinding himself against him, it was almost exactly what he had wanted Leatherhead to do to him, to overpower him, pin him, use him. 

“Oh god…” Donnie breathed out, tears streaming down his cheeks as he started slowly rocking his hips. 

He kept his eyes closed, feeling the hot breath on the back of his neck as Leo churred, rocking against him in short quick thrusts, the tip of his cock catching on Donnie’s entrance. On reflex, Donnie pressed back against it, forgetting for half a moment that it was Leo’s cock, however, that split second cost Donnie everything and he knew it. 

Leo was moving in quick short thrusts, and Donnie was rubbing himself against the bed just as quickly, he was so close to completion. He put every thought of Leo aside and simply felt the weight on him, the cock sliding along his ass, leaving a slick trail of precum behind, and the feel of the blankets rubbing at his own cock. Donnie churred, moaning loudly as his muscles locked as he came, jet after jet of cum soaking into the blankets and sheets under him. 

Leo was transfixed by the sight beneath him. He loved watching Donnie cum, had jerked off multiple times to it, however, this was the first time he had ever been so close. He felt the muscles grip him and he grunted, gripping Donnie’s ass, squeezing him around his cock as he too gave a few more thrusts, and he was cumming next, his seed painting Donnie’s tail and dripping into his ass. 

Leo kept moving until he had milked every last drop from himself, before sitting back, spreading Donnie’s cheeks wide to watch the sticky substance run down between the cheeks, dripping between Donnie’s legs to mix with Donnie’s release soaking the bed. 

Leo knew then, he was fully obsessed with his brother. No matter how far away Donnie decided to move, Leo would fully own him one day, it was a silent promise to himself as he leaned over Donnie once more, turning his head to kiss his brother’s cheek. 

“You are perfect, never change,” he whispered and then Donnie was left alone. 

It would be a long time before Leo saw Donnie again and the day his brother walked into his company for an interview, was probably the second happiest day of Leonardo’s life.