Who is Debbie Marcus from Deadly Little Secret and what is their importance?

Debbie Marcus is the young girl who is rumored to be stalked by Ben. After the police get involved and threaten Ben, Debbie is hit by a car while walking home one night. Everyone believes that Ben was the driver. In the end, we learn that Debbie's being stalked was actually a practical joke perpetrated by her friends.... Ben had nothing to do with it.