My memories are vague but I recall the basic teen girl moves to a new town but there are ruins(?) nearby for some reason. The main monster is a feathered basilisk creature from an old cave? I also remember it being venomous and that the final fight happens on the ruins. To be honest I'm almost 30 but not being able to remember this still bothers me as my kids get older and ask to read some of my old books, please help.