Headache

This is a Bakugou x reader/oc starting around the time of the sports festival as your character tries to transfer from general education into the hero course.
Your character has a unique quirk: They can slightly alter people's brain chemistry through skin or blood contact. Without proper training, they can only comfortably change someone's melatonin levels and have minor experience with slightly changing someone's serotonin and oxytocin levels.