The Muggle-Born Pureblood

Hermione Granger returns after the war to finish her seventh year at Hogwarts. She gets Head Girl and finds, to her suprise, a returning student from her year has become Head Boy. When she find that he has changed for the better, she can't help but let her feelings get in the way of just friendship. But what happens when he learns her big secret? Why was she hiding it from him?