bakudeku

Izuku and Katsuki had been a couple since middle school, but Katsuki's pride complicated the relationship. The blond boy loved him, but the problem was their lack of communication. Izuku would fight with him; they argued more and more. It got to the point where he really didn't want to talk to him. Izuku put everything into the relationship but received nothing in return.
Hatsune asked Izuku for help as a test subject. Izuku helped, but when he thought it would be an explosion for his "baby," the prototype that was going to be a boy with a teleportation quirk, a man similar to Katsuki, only more "wild" and medieval, emerged from the smoke of the explosion. The wild Katsuki didn't separate himself from the modern Izuku.
After the incident, medieval Katsuki was the complete opposite of his boyfriend; he paid attention to him, showed him affection, and cuddled him. It turns out that medieval Katsuki had a husband, and that was the one from the past, so in his view, it seemed normal to do it with modern Izuku.
But the one who wasn't happy was Katsuki, jealous of seeing him happy with someone else.