Who is Debbie Hemlock from Killers of the Dawn and what is their importance?

Debbie Hemlock is Darren's former girlfriend. When she is taken hostage by the Vampaneze, Darren plans to free her when the group returns to the tunnels. Debbie, however, is set free before Darren is supposed to fight with the Lord and ends up helping Burgess fend off Vampaneze while Crepsely tries to kill the Lord.