I don't think I've ever seen a bad character evolve into a good character. I've seen some good characters become even better characters (e.g. Nathan Drake, Revolver Ocelot, Big Boss), some good characters become bad characters (Yuna and Rikku from Final Fantasy X to X-2, and Raiden from MGS2 to the newer games), but never have I seen a bad character become a good character.
My remark about Raiden probably deserves an explanation. He wasn't a likeable character in MGS2 but he was definitely well written. In MGS4, he was poorly written, and his only redeeming factor was coolness. I haven't played Revengeance, but I imagine he's not a well-written character even in that game.