There have been many other villains that have tried to evoke this kind of charisma, where you aren't sure of their stability, but you are sure that they believe strongly in what they're doing. For some, it is controlling the world. For others it is simply money or survival. Vaas is a good example to get this started, but aside from his excellent monologue, we don't know enough about him. The Jackal, your target in Far Cry 2 might be a good way to get things started. He is an intriguing character...