Possessive!Boyfriend!Arisu Ryohei x Sub!Reader
Summary: Arisu doesn't like the idea of you spending time with mentor and friend, Chishiya, who's assisting you on your PhD dissertation. He develops a possessive attitude which prompts you to prove your loyalty to him.
Word Count: 3.2k+
Warnings: jealous!Arisu, angst, fluff, smut, sub/dom dynamics, daddy kink, graphic language, slight!tipsy/drunk Arisu, traffic light bdsm system, spanking, hair pulling, biting, markings/hickies, finger sucking, light degradation kink, brief nipple play, creampie, breeding kink, dacryphilia, orgasm denial/delay, p in v (unprotected), oral sex (m receiving), fingering, sex positions (full nelson, doggystyle, reverse cowgirl), lots of pet names (sugar, prince, baby and so on), fluffy aftercare/happy ending
They say there is no greater glory than love, nor any greater punishment than jealousy. Arisu's love for you results in the consequence that he loathes seeing you with any other man aside from him.
It's not like he's unreasonable. He's fine if you have guys friends...just not guys like Chishiya. It just wasn't a fair fight. Chishiya's really smart, a doctor, AND—the kicker— he was handsome.
And, sure, Arisu felt as if he had '2 out of 3' of those things listed but what he felt really set himself apart from Chishiya was how cool Chishiya was. He didn't have to try. Women and even men are naturally drawn to him just based on first impressions alone. Meanwhile, Arisu was an unsociable loser who would rather play video games for hours on end than strike up a conversation with a stranger.
Why did you have to choose Chishiya of all people to help you with your dissertation? And now you're in a residency program working in close quarters with him, too?!
Arisu could see it now. He paces back and forth in the apartment the two of you shared creating hypothetical scenarios.
What if....One day, you and Chishiya are working in a room together when the two of you 'accidentally' touch hands. Next thing you know, the two of you are making out and ripping each other's clothes off in a room meant for a patient needing heart surgery!
He shakes off that silly imagination. No! You wouldn't possibly do something like that to him. You love him. You wouldn't just cheat on him but what if....you broke up with him instead?! That way you wouldn't feel guilty for being with Chishiya instead.
Arisu bangs his head against the island table in the kitchen when he decides to call his friends over for some drinks and very much needed advice.
"You should just tell her how you feel," Chota begins. "You'd be surprised to recognize what you discover about yourself when you speak about your feelings with her. Shibuki and I are going strong because she taught me how to be more open."
"No offense, Chota, but that's pussy advice," Karube remarks. "Whenever my girl does something I don't like, I lay down the law. I put my foot down," He slams his beer on the table for dramatic effect. "Works every time."
"Is that so? Because last time I checked, she made you cry that one time she threatened to leave you. Didn't see any laws being laid down." Chota chuckles.
"Up yours, man." Karube bites.
"You guys aren't helping me feel any better," Arisu groans. "The girl of my dreams is slipping away as we speak. For all we know, Chishiya's already asking for her hand in marriage."
"You could always try rebounding if she does dump you. What about Usagi?"
"No way! She's only a friend. Y/n's all I ever wanted. I've imagined my future and she's always in it. I won't let her go." Arisu says, determinedly.
