It was after the failed extermination in hell, where many exorcists died as well as Adam, Lute's superior. Lute made it out alive but not without her own sacrifices. She lost her left arm and was covered in cuts. It was a miracle she didn't lose her wings. When she returned to you, her partner (you can be an angel or demon), who ran to her with concern, which she quickly shot down.

"I'm fine." She hissed, clearly lying.