Big Bad Potter

Teddy Lupin was the first of his kind, a child born of the union between a metamorphmagus and a werewolf. But what if this wasn't the case? What if there had been one before him who shared the circumstances of his birth? Enter Harry Potter, Boy-Who-Lived and average third-year student... or so he believed. AU, Meta/Were(kinda) Harry, Harry/multi, crossposted to ao3