Chat noir finding out Ladybug is crushing on Adrien, (his civillian self). So he starts badmouthing himself and watches her defend him. Ladybug getting angrier and more frustrated. Defending him more and more.

“Of course you would defend him. You’re just a fan. It’s not like you Actually know him”

“Know him?! I sit behind him in class!”

Chat noir just pauses. Eyes go wide.

Ladybug realizing she said too much.

“Alya?”