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Kaminari groaned, turning over beneath his covers. He really needed to sleep, but he knew sleep wouldn't come. Not after Monoma had so liberally flexed his dynamic on Kaminari during their joint training that day.
He absolutely hated the whole Dom/Sub dynamics thing. He hated how he was one of the only male Subs in class, in the whole Hero Course! It wasn't really that surprising, Subs were more common in the General Course because it was hard for Subs to become heroes. Some still made it though. Kamui Woods was a Sub as well as Bubble Girl. Probably most surprising of all was Mr. Aizawa. With a quirk like his, it would have made more sense for him to naturally be a Dom, but no. He just rarely reacted to any Dom other than All Might, Present Mic and Midnight.
Midnight was a special case though. Everyone reacted to her. It was a special part of her quirk, but Kaminari wasn't mad about that. Who would be?
He also hated his dynamic because he could feel his body react to any Dom in the area, especially if he didn't take his suppressants regularly. If he missed a day or his time was off, he would be fighting his instincts all day. If Mina was irritated and cut a glare at him (which didn't happen often, but still), he'd be on his knees in an instant clutching at her ankle until she let up.
He noticed though that in his case, it was a little easier for him to resist Doms who didn't have a personal bond with him. If it was Kirishima, Mina, Jirou or Sero though? He was a goner.
The only Dom he never reacted to was Bakugou which was probably the most curious thing about the dynamics. Bakugou was always angry and raising his voice, but never once did Kaminari react to him. It was almost like he was a Sub, but that didn't make any sense because he never reacted to anyone.
Bakugou was indeed an anomaly, but he must have just had an extremely weak dynamic. Or he never flexed his dynamic which also didn't make any sense for his personality.
Kaminari's biggest hope for making it as a Sub Hero was finding his Pair early on. If he found his Paired Dom, then he'd be set. Once a Sub found their Pair, they would never react to another Dom's commands unless that Dom had an exceptionally powerful dynamic like Midnight or All Might.
He never wanted to meet someone like that, but he'd heard that Shinsou had a strong dynamic. He'd had very few interactions with Shinsou since the Sports Festival, but every time they talked, there was a sharp tugging in his chest. He had to wonder what it was, whether it was his natural instincts to react to a strong Dom or if it was something more, but he wouldn't know without truly submitting to Shinsou. He wasn't ready for that as much as he boasted, so he'd just have to wait.
What he couldn't wait for was sleep.
Sleepless nights happened few and far in-between for him, but when they did, they really were sleepless. He'd just lay in bed until his alarm went off in the morning, so usually, he just found something else to do. Or found someone else who was still awake to bother. Generally, he just went to Midoriya who was the only other person who had the occasional bout of insomnia and could help him during times like this without needing anything in return.
So, he wasn't surprised when he padded down the dark hall to find light filtering from beneath his door.
Knocking lightly so he didn't wake anyone else up, he pushed open the door when he heard a soft mumble in return.
He was not expecting to find Midoriya sitting on the edge of his bed with Bakugou between his knees, head pillowed against Midoriya's ample thigh. A thin black leather collar hung loosely from Bakugou's wrist.
Midoriya nodded off, head dipping and lifting every few seconds. His hand was buried in Bakugou's blond spikes, completely still in his doze.
Bakugou looked completely blissed out in his sleep. It was the calmest and sweetest Kaminari had ever seen him look.
His heart raced and jealousy bloomed hot and green in his chest. Frozen in the entryway, he could only stare at them.
'Katsuki is a Sub. Katsuki is a Sub. Katsuki is a Sub. Katsuki is-'
"Holy crap, you're a Sub!" Kaminari shouted before he could stop himself.
Bakugou and Midoriya flung themselves away from each other. Katsuki hit Midoriya's desk with a grunt. Midoriya slammed against the wall by his bed and groaned. The collar flew through the air before landing and rolling to a stop at Kaminari's feet.
The soft air of the moment went up in flames.
"What the fuck?" Bakugou snarled, glaring from Kaminari to Midoriya, "Fucking Deku! I thought you said you locked the door!"
"I thought I had!" Midoriya gasped breathlessly, clutching at his chest, "What are you doing here?"
"I couldn't sleep because of what Monoma did earlier, and I knocked and heard you reply, so I came in, and... and..." His mind leaped for the only logical conclusion. "You're a Pair!"
"Shut it, Dunce Face! Do you want the whole damn dorm to hear you?"
Kaminari paused, pulse still thumping hard enough that he felt his skin pulsing along with it. Dropping his voice, he whispered, "Is it a secret?"
"Well, it sure as fuck ain't advertised!" Bakugou snapped, as irritable as always.
"'Stop'," Midoriya sighed, sliding to the edge of his bed again. They both went still immediately, and relief flooded through Kaminari at the gentle command. "'Kneel, Denki'."
Kaminari sank to his knees with a shuddering sigh of relief and pleasure, and Bakugou glared over at Midoriya.
When Midoriya spoke next, it lacked the flex of his dynamic. "Don't look at me like that, Kacchan. You don't have to deal with being forced to submit like Kaminari does, and you don't realize the strain it puts on his body. We've been through the classes, but it's not the same as experiencing-" He cut himself off with a shuddering sigh. "Class doesn't explain it because the curriculum is geared more towards Doms. It's not like I'm going to do anything with him, this just helps mitigate the effects from others."
"And how often do you two have this little pow wow? Were you going to tell me, or just leave me in the fucking dark?"
Kaminari snorted, and did his best to stifle his giggles. This was the first time he had ever heard Bakugou sound like a jealous boyfriend. It was more fun to watch than he thought.
"What the fuck are you laughing about?" Bakugou snapped at him. The effect was lessened by the fact that not only were they both on the floor, but Bakugou was still propped up on his arms from when he'd thrown himself away from Midoriya.
"It all just makes so much sense now." Kaminari grinned widely. "I'm glad you have your Pair. I mean, I don't think you would have gone through what I do anyway. You're so stubborn, you probably wouldn't react to a Dom's command out of sheer force of will. But it's better to never know, right?"
Bakugou narrowed his eyes, but glanced away, red tinging the tips of his ears and his cheeks.
Midoriya smiled at him. "I probably don't have to ask you this, but um, our relationship isn't something people know about? We'd rather keep it under raps, so if you could..." He trailed off meaningfully.
It took Kaminari a moment to understand, but when he did, he grinned. "Don't worry. Your secret is safe with me! Who would believe me anyway? But I guess this means I should probably find another Dom to help. Don't want to step on anyone's toes or anything."
Midoriya caught Bakugou's eye, and after a moment of silent conversation, Bakugou huffed. "Whatever. It's fine as long as you don't do anything together. Until you find your Pair or a Dom, I guess."
Kaminari launched himself onto Bakugou. "I'll look real hard, I swear! You're such a good friend, Bakubro!"
"Don't call me that, Dunce Face, and get the fuck off!" Bakugou snapped, but not as harshly as normal as he shoved at Kaminari's body, "Now, if you're all fixed or whatever, get the fuck out."
Kaminari took a moment to take stock of his body, and while the tightness in his chest was still there, it was less than before. Now, he just needed to calm down, and he could take walk to accomplish that. "Sure thing."
"Wait, are you sure?" Midoriya stuttered, and Kaminari grinned back.
"Yeah! I'll see you guys in the morning!" He pushed himself to his feet and headed for the door. "Don't do anything I wouldn't do." Scooping up the collar on his way passed, he tossed it back to Midoriya who fumbled to catch it.
Before he closed the door completely, he paused to peak back and watch his strange pair of friends.
"'Come'," Midoriya murmured quietly with a gentle flex in his voice. Bakugou crawled willingly back to him, expression exhausted as he found a comfortable seat between Midoriya's knees again. When he settled his head on Midoriya's thigh, head craddled in his hand and their fingers twined together, Midoriya began murmuring too quietly for Kaminari to hear.
The serene air from before settled back into place as if it had never been disturbed.
Bakugou hummed in response, just a quiet rumble in the room, and Kaminari finally shut the door silently.
Padding down to the common room, he found his way out onto the street. He breathed in the cold night air, clearing out the rest of the excitement and knots in his chest. He wondered if those knots were panic, panic at being commanded by someone he didn't trust, panic at wondering if that person was going to command him to do something he didn't want to do, panic at not having a say in what happened to him during those times. Nothing terrible had happened so far, he'd been lucky. There were horror stories of Doms abusing their Subs, and it terrified Kaminari every time someone commanded him that it might be his turn.
The scrape of shoes close by startled him bad enough that his heart started racing all over again. Spinning around, he found Shinsou staring sleepily at him.
"Sorry," Shinsou said in his deep voice, scrubbing a hand through his purple hair, "Didn't mean to startle you. Didn't expect anyone else to be out this late."
The tug was back, strong and insistent as it always was when Shinsou was near. They stared at each other. "I couldn't sleep."
"Same. I don't sleep well. At all really."
They lapsed into silence, and after a moment, Kaminari mustered up the courage to blurt, "Do you have a Pair? Or a Sub?" Heat crowded his face, and Kaminari wanted to chide himself. After seeing Midoriya and Bakugou though, feeling that immediate jealousy, he thought he might have been more ready than he first realized.
When Shinsou considered him for a moment and said, "No, never really thought about it or had the chance," he knew he was ready.
Kaminari smiled despite the heat in his face. "Do you want one?"