Foil
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Character Role Analysis
Maz
Maz actually works quite well as a guide/mentor too, but she just shows the heroes the path; she doesn't guide them along it in the way a true mentor might.
In fact, she challenges Rey and Finn to look at parts of themselves that they'd rather not, which is the kind of thing a foil tends to do. We'll plop her in that category for now, with a bookmark reading "wait and see" for the next Star Wars film she appears in.