Mentor Faerie Friend: Design Help?

This part I'm not 100% how to go about. I have a new player entering the game that is of House Merinita, Fae-Upbringing, Giant-Blooded, and Faerie Friend traits being the most relevant. They were hoping for the fae to be weak enough to justify appear roughly every other session, and serve roughly as a mentor figure. I'm having a bit of trouble designing such a character for them, both in narrative construct and faerie powers. I was thinking of it being some kind of Merlin analogue, but for some reason I'm coming up with a blank for its actual role in day-to-day sessions (and appropriate abilities/powers).

Mentor -in what-? To -what end-?

Also, you don't need to stat the faerie out. Faerie can change their stats (or even have others step into their roles) between scenes. This means the faerie persistently has the stats required to do what you need it to do, and you can just construct it as you go. Out of a pool of points, if you like, or just with pure ad-hocery.