Parvati is a Gryffindor fifth year. She has no real role in Book 5 except as an active participant of Divination class: she loves Divination and respects Professor Trelawney, so she is distressed by the clear signs that Professor Trelawney is losing it under pressure from Professor Umbridge. Parvati also tries to talk astrology with Firenze, only to discover that she is way out of her depth. She tries to tell him:
Professor Trelawney did astrology with us! [...] Mars causes accidents and burns and things like that, and when it makes an angle to Saturn, like now – [...] that means people need to be extra careful when handling hot things — (27.42).
Firenze dismisses all of this as "human nonsense" (27.43), disappointing Parvati. But her enthusiastic faith in Professor Trelawney's astrology underlines that Parvati is vaguely silly and not very serious – about as far from her Gryffindor dorm mate, Hermione, as she can get.