"Tilt your head to the side, Potter," Harry, who had been lost in his own mind, did as Snape asked, watching with trepidation as the man approached him, the pipette of the vial with no number already preloaded with two or three drops of clear liquid. Harry didn’t know why he kept trying - it always stung and burnt, and healed him to some extent, but it never lasted long. He could often feel his skin peeling back open long into the evening following these appointments.