"what if i don't want this fight?"
The first time they really meet is in a battle of head versus heart, humanity versus the monster inside. She doesn't really want to fight, she never really wants to fight — she just does, because it is a way to survive, and surviving is all that she has ever done.
So she doesn't want to harm but she does. It is cruel, cruel world, and she long ago learned how to survive in it. Self-preservation is her first instinct, and even though the man in the fallen mask is not fighting to kill she's afraid to know what will happen if she gives in to his aura of peaceful loneliness.
She doesn't find out. Soon the battle is hers. And suddenly her rage towards him for abandoning her on Jakku pays off and she watches as he falls onto the ground, crimson pooling around his face. She remembers that face, the face which used to comfort her in times of need. Ben's face.
She can't kill that face. And then suddenly it is all cracking and crumbling and the earth is spewing its hate at her but all she can think about is that she's finally away from him, that she doesn't have to kill him today.
Strangely, she is glad.