And how do you know that she enjoys the pain? Have you ever seen her smile when she inflicts/recieves pain? Don't be so quick to deamonize her. Her "sick twisted nature" is probably nothing less than out of her control. I agree that she might not be able to control herself when she fights. But it's most likely not the way you view it. It's not like: "Oooo a fight! I'm gonna tear them to peices!" because that's Tiras mindset. Pyrrha's mind to probably like: "Oh no! Someone's trying to hurt me or is intimidating me! I don't know what to do!" then probably shuts down and something intervenes. A force that literally forces her to fight and finish it before she can leave. That's why she cries when she wins. She dosen't understand herself as to why she even fought, feels guilty, and then runs away.