During the events of A Matter Of Principals, a certain draconequus spits a brief yet sharp comment at a friend of his that ends up getting him physically banished from school. After the matter is resolved, Discord feels he's back on good terms with ol' Starlight.

Until a dragon friend of his tells him that he's soo NOT good with Starlight. Not until he makes up for it.

(Written directly after watching the episode LIKE WTF DISCORD MAN YOU DON'T CRITICISE FELLOW VILLAINS LIKE THAT GOSH)