Who is she?

When Stiles sees a girl named Allison, that he have never seen before he immediately becomes interested. He takes her to the local dance. They almost kiss but they don't. Allison has liked Stiles for a long time be he never knew she was even there... Until now. They get to know each other very well. Allison invites Stiles to come and study at her house but it quickly becomes something more. They start to date. But Allison got stabbed by an anonymous killer and she dies in the arms of her brother Scott. Stiles is devastated.