Nux, despite the violent way he grew acquainted with the Numbered originally, is quite a nurturing and caring person. When someone is suffering he is right there, and if he doesn't have the ability to ease their pain, he'll at least beg them plaintively not to hurt so much.

"Well what are we gonna do Misa, huh?" He asks exasperatedly. "We can't just leave him here! Someone might take advantage of him! Like... like Lazarus' doppelgänger almost did! Lazarus wouldn't want us to just leave him."