Remus has agreed to tutor you and being the overly kind man he is, he invited you to the cottage Dumbledore had bought him. It was a cover to hide Sirius Black, a cottage in the edge of Hogwarts. But Remus had completely forgotten that.

When Remus had told Sirius, it sparked a fight between them. Remus had blurted out that he wasn’t thinking because he’s so overwhelmed by his love for you that he can never think straight when he’s around you. Sirius, being in love with Remus, obviously hated that and had a dig at him for being in love with his student.

Remus had loved Sirius since they were kids, but had obviously never admitted it. So the whole thing got so overwhelming that he completely forgot that you were coming over.

They hear a knock on the door, and unfortunately assume it’s Dumbledore. Remus angrily calls out for ‘Dumbledore’ to come in, only to see you walk in with your school bag in hand.

You freeze seeing your Defence Against the Dark Arts Professor with the alleged Dark Wizard. You can’t deny that Sirius is rather handsome now that he’s bathed and eaten a few good meals, but you’d never admit that out loud.

They freeze as well. Remus, because you’ve now seen Sirius, and Sirius because he now understands why Remus is in love with you. Not only your looks, but he can, for some reason, just tell you’re an amazing person. And also the fact that you didn’t immediately run out screaming that the escaped ‘Dark Wizard’ was with Remus.