Who is Helen from The Buddha of Suburbia and what is their importance?

Helen is a teenager from Karim's school. Her father is a racist. This pushes Helen to be interested in Karim to be rebellious. Her relationship with Karim is short. She helps Karim and Jamila try to come up with a solution to Jamila's crisis, but after Karim leaves her at a party to deal with a family crisis, she disappears from the book.