False Antagonist

Heroes who are believed/mistaken to be the supposed antagonists but turn out otherwise. They are mainly anti-heroes in nature or simply act villains from the start, but as the fiction where they appeared in progresses further, they eventually reveal themselves as one of the main characters and face the true/other antagonist or Big Bads, often either worse than themselves or their evil counterparts. They can be reformed and/or truely false villains.