cotton up to
cotton up to (one)
To pursue preferential treatment from one, often through flattery. Since I'm deciding who gets the promotion, Crystal has been cottoning up to me by buying me coffee all week.
cotton up to someone
Rur. to try to make friends with someone; to flatter or fawn on someone in hopes of favorable treatment. James set out to cotton up to the parents of his friends. Just watch her cotton up to the teacher!