[A lot happens all at once, just then. It seems that the moment Izuku bites down on Katsuki's neck, maybe even a little before, he ends up cumming from it. Not only that, he tightens down on Izuku so much that he fears for a wild second that he won't be able to move anymore. Fortunately this ends up not being the case as Izuku moves on automatic, all other thought erased other than one: to mate. Breed. Make Katsuki his.
With one punishing thrust of his hips forward, the base of his cock makes it past that ring of muscle and into Katsuki's body as Izuku knots him, firmly locking himself in place as he cums shortly thereafter with a thick sound through his teeth still latched onto Katsuki's neck. He cums, and he doesn't really seem to stop right away either, shivering from the shoulders down.]
no subject
With one punishing thrust of his hips forward, the base of his cock makes it past that ring of muscle and into Katsuki's body as Izuku knots him, firmly locking himself in place as he cums shortly thereafter with a thick sound through his teeth still latched onto Katsuki's neck. He cums, and he doesn't really seem to stop right away either, shivering from the shoulders down.]