"My Only Light" Severus Snape Love Story

Mercy is 17 years old and goes to Hogwarts. She carries a secret with her as she returns to Hogwarts for her 7th year. The last time she was at Hogwarts it was her first year and not her best. She caused a lot of trouble. Will she cause so much trouble when she returns? Will everyone find out who she really is? Will...