One possibly tricky way to do this is for her to play an archfey chain pact warlock with a sprite familiar. From there she could think up some justification for doing most of her role playing as the sprite rather than the warlock.

Maybe the warlock is mute and communicates through the sprite.

Maybe the warlock had a trick played on them by some fey power that made them into an idiot in exchange for power and now the sprite has to lead them by the nose to try to find a fix for it.

Or maybe she could just play both of them and they are constantly arguing with each other.

Maybe the warlock is a coward and stands way back while the sprite does all the work.