AU. When Lily died, Snape removed his heart and replaced it with a steel trap. But rescuing her daughter from the Dursleys in the summer of '92 is the first step on a long road to discovering this is less true than he'd thought. A girl!Harry story, covering CoS - GoF. Future Snape/Harriet. Sequel "No Journey's End" (Ootp - DH) is now posting.