She is 16 years old. She is an agnostic (she rejects religion but is not disinclined to accepting the existence of God), which puts her at odds with the real Jeanne d'Arc who was a devout Catholic (this was once explained by feeling unable to live up to the real Jeanne d'Arc). Joan makes home-movies to express herself artistically. In the episode "Makeover, Makeover, Makeover", Abe prints flyers of her in order to get her a date for the prom and the flyer describes her as "Janeane Garofaloesque".