For me, the easiest way to make a villain is to find out what other people call him/her. Once I know that I can flesh the rest of his character out. Because people will not sugarcoat what you are, they will be honest about you. I do this with all my main characters actually.
What People Say About Her-THE GOOD
What People Say About Her-THE BAD
History: She was banished from her home planet because of wanting to engage in a death duel. On her planet death duels are the final straw when you feel you cannot resolve matters peacefully with someone. However the government does everything they can to try to persuade opposing parties to make peace. When that fails, the opposing parties are sent to a duel chamber that is closed off from public viewing. There the potential combatants are told that they have one last chance to call off the fight. If they both still want to fight, they are both banished immediately off the planet. If only one wants to fight and the other refuses, then the consenting one is banished. The one remaining is thought to be the victor off the fight by the public that does not know any better. The matter is kept secret on pain of banishment.
In Rana's case, she was the consenting fighter and so was banished, while the other did not want to fight. Ever since she has been with other alien species and other banished Murkons, wanting to return to her home planet to overthrow the government there. And thereby reinstitute the polices of old her world had long ago. Like REAL death duels. Not the mock ones that they currently do covertly. On the plus side the crime rate on the planet is currently nil.