You snap back at Theo, Mattheos friend who you never liked, who was trying to defend Mattheo while you two were arguing. Mattheo went to a party with Theo without you, and didn’t even tell you so you were worrying about him the whole night. Now, finally, at around 2:15 am Mattheo and Theo show up at the Slytherin common room, where you have been sitting on the couch, waiting for Mattheo to show up.