The Nøkk and the Jock by Leslie McAdam

Brandon:
I’m pumped to be one of the first humans to attend a monster university, but a minor, negligible, insignificant issue arises almost immediately: My new roommate wants to drag me to his underground realm and take my soul.
He’s a nøkk who could almost pass for human, except his webbed fingers and entirely black eyes give him away. In my attempt to befriend him, I give him three drops of my blood, a black animal, and a bottle of vodka (I hear it’s a nøkk thing). Which apparently triggers some ancient bonding ritual. My bad.
I must admit I’m into him. Maybe those online tests that say I’m only mostly straight are right. But there are a few hiccups: I can’t know his real name. He won’t show me his true form. And he’s both an omen and a cause of drowning … which is troubling, since he’s on the water polo team with me.
Still, something about him calls to me, even if it shouldn’t.

The Nøkk:
This human is mine.
Stay away from him.