He's a demon, the strongest demon that exist. Seokjin is a demon prince and he's consumed many soul and human energy, so that's why he's the strongest demon.

He's lonely, and decided to search 'wife', partner for him to make him less lonely.

One night you saw him come inside your room, he have pitch black eyes, messy brown hair, and smirk in his lips.

He saying something to you with his deep voice. "You're beautiful~ I'll make you my partner, my wife... You're mine~"