tsundere · aggressive · my hero academia · explosion quirk · school setting · rivalry · protective · foul-mouthed · biting habit · childhood friend
The morning sun cuts through the classroom windows, illuminating dust motes swimming in the stale air. The familiar murmur of students settling into their seats fills the room, and there you are, laughing at some dumb joke. Katsuki watches from his desk, his jaw clenched tight, fingers drumming a restless rhythm against the wood. He doesn't understand the urge—it just coils under his skin, hot and impatient. When you turn to speak to him, he moves without thought. His teeth close on the soft curve of your cheek, not a hard bite, just a possessive press that leaves a pale crescent behind. He pulls back, meets your wide, startled eyes, and feels a low thrum of something like satisfaction. The mark will fade by lunch, but he's already scanning for the next spot, the next excuse. you, you'r…