I didn't really get the ending until I remembered: Merle told the Governor that he killed Michonne. That fact alone, mixed with the loss of his "daughter" and the loss Woodbury suffered, could drive him to view Merle as a traitor. After all, we've seen how vicious he can be.

I didn't really get the ending until I remembered: Merle told the Governor that he killed Michonne. That fact alone, mixed with the loss of his "daughter" and the loss Woodbury suffered, could drive him to view Merle as a traitor. After all, we've seen how vicious he can be.