Kaminari has always thought the idea of soulmates was cool, ever since his mum had told him. The idea that, no matter what happens, they'll be at least someone out there for him. Someone who will love him unconditionally, even if his mother can't. It's what he clings to the day she disappears. He doesn't need her, he's got a grey mark on his shoulder and he imagines it's his guardian angel. He's looking out for him until they meet. It's the place he clings to when he's upset, his other mark however. Well, Kaminari has been unlucky in everything else in life, so why would this be any different? His other patch of grey skin is in quite an intimate place. Every home passing him on as quick as they can as soon as they notice the mark. He never really understood why, yes it was a weird place, but he was too young to know the meaning. He figures it out when he's older, but by then he couldn't care less anymore. He's numb to everything, well, mostly everything. He puts on a visage of this happy-go-lucky dumb kid and somewhere along the line, it actually stops being an act. He's not particularly fond of the mark, but he doesn't hate it, mostly it's just embarrassing. People still tend to make fun of him if they see him bathing, changing or showering and he learns to deal with it. So of course, he isn't surprised when it happens at UA. He expected at least someone and Bakugou does exactly that when they're washing before their baths. He teases him and then offers to see if he's his soulmate and grabs his dick. Denki leans forward instinctively and Ejirou puts a reassuring hand on his shoulder, telling Bakugou off. His shoulder turns red and his dick turns orange. Denki and Ejirou are surprised, but Bakugou finds it positively hilarious, exclaiming, "You have an orange fucking dick!" Then he corrects himself and says, "It's my orange dick now." He licks his lips and Denki hides his face, blushing. "What about you Kirishima, want an orange dick too?" Bakugou laughs menacingly, approaching his friend.
"No," Kirishima says quickly, backing away. Bakugou tries to grab his dick anyway, but ends up grabbing his balls instead. (Kirishima hasn't been teased, as most people don't notice the grey in that place.)
"That's even better!" He shouts, laughing. "I've grabbed you by the balls!" Ejirou is bright red, but Bakugou just continues to laugh and pulls him into a hug. Kirishima's hands push on Bakugou's chest, changing the two grey patches red and he's surprised, assuming one had been for Denki. Denki instead comes up behind him and breathes into his ear. He grabs his arse, his small fingerprints littering the cheek, his middle finger pushing into his hole slightly, part of his palm covering his cheek. He'd never noticed it before, so was taken by surprise. The grey hadn't been very noticeable, but the yellow is obvious now.
Bakugou went red and Denki whispered in his ear, "Who owns your arse now?"
"You're an arsehole!" He shouts.
But Kaminari just laughs, having fun getting his own back and saying, "Yes, you're arsehole owner." Bakugou is bright red, completely beetroot and pushes them both away, stomping off to the warm baths. Denki grabs Kirishima's hip, trying not to fall, it's not the best place to grab, but Kirishima catches him and his hip turns yellow. Bakugou is already hiding in the warm water when they collect themselves. They laugh about what's just happened, before joining him. They cuddle into him and he grumbles, but doesn't push them away.
UA has been good to him so far and Kaminari feels at home, but now he feels really at home. He's found the pair who will love him unconditionally and he'll never be alone again.