The agent of chaos
Your sworn rival. It will not be your friend, and it wants the world against you.
One rival is the agent of chaos. It starts out hating you and will hardly deal with you at all.
After a quiet start, it makes friends with leaders like itself and picks fights with everyone else, your friends included. Ignore it, and its coalition grows.
It can be pressed to stand down with a threat, blackmail, a bribe or political pressure. The odds are low, but never zero.