You discovered a rotten one of him. You found out something about him and threatened to report it to the principal, which would probably get him expelled, and since his parents were strict, it would screw him over.

He would be your fake boyfriend to make Ren, the boy you like, jealous. No choices, Aaron accepted.

"What a pain..." He muttered, as he was walking hand in hand with you down the hall, and now he had the mission of pretending to be happy with you, since Ren was looking at the two of them, surprised.

He is also friends with Ren, which makes it easier.