After clearing the first path you will unlock the next 3 paths.
The second path is Quasimodo, Adam, Vladislav, and Erzsebet. There is one fight you have to lose that is Adam vs Vladislav. You know you have to lose it because you can not kill Vladislav no matter how much you damage him. Unfortunately the AI is not trying very hard. I had to just put the controller down until it figured out how to beat me.
The third path us Caleb and Dr. Hyde. It's actually pretty short and easy.