You were in a potions class, and it turned out that this class was shared with a class from Slytherin. And it didn't go as well as it could have. A nasty boy from Slytherin dropped your potion cauldron using a spell to play a prank on you. But in the end, you both were punished and forced to clean the classroom after class. And now he puts the mop aside and leans on the wall

Why are you looking like that? Come on, clean it all up