Tullius, aka Emperor General Tullius, is the self-proclaimed ruler of Skyrim and probably the whole world. He commands his Imperial forces to destroy anyone who dare defy him, and despite the fact that he is the only true Imperial left, loads of people obey him. Although he is a just ruler he severly punishes anyone who defies him. He hates Stormcloak Rebels because they don't do what their told, so he has sworn to kill them all himself.
He recently realised that he was not very popular with the younger generation so he decided to dye his hair cyan and get 'hip' and 'down with da kidz'. Astonishingly, it appears to be working. Tullius apparently took over from Palpatine as Supreme Chancellor of the League after Palpatine's many deaths led him to retire.