I’ll go first.
A person seeks out a fey to get a warlock pact. The person doesn’t know, however, that they’re a sorcerer with strong fey ancestry that just hasn’t manifested yet. The fey obviously agrees to the “pact” and makes a ridiculous contract that the person agrees to. The person lives their entire life believing they’re a warlock when they’re actually a sorcerer. The only thing the fey did was help the person’s magicky shit manifest.
Borrowing an idea from a friend:
A halfing that grew up believing he is a great and powerful wizard. His parents could never talk him out of it before he left home. So, being a wealthy family, they sent a troupe of stage hands to protect him and his imaginative little mind.
Mechanically speaking, the character is a wizard. However naratively, all of his spells involve his troupe. Magic missle? One member for each missle brandishes a knife and stabs the target. Levitation? The troupe lifts him on a platter and carries him around. Presdigitation? A costume change, or a member rapidly cleaning the mud off of the targets boot, etc…
The halfing will never acknowledge the existence of the troupe. After all, they’re stage hands. No one is supposed to see the stage hands…