It couldn't hurt to humor him and joke around a little. Lisa was serious about her work, but they weren't talking about that now. She'd grown rather fond of Draco during her time at St. Mungo's. She hadn't really spoken to him at Hogwarts, but working together brought out something different in people than going to school together. She appreciated his brand of humor and work ethic, so there was no reason for her to dislike him.
"I think that's ill advised," she reminded him. "Remember, healing means make it better, not make it worse. And the sooner you heal them, the sooner they're gone."
That had been Lisa's motto, though she hadn't dealt with many patients. She had mostly done disease research and would act as a nurse for the sake of sampling in some of the more rare cases. Regulus Black had been a piece of work when she'd taken his samples, but that was neither here nor there. "Do behave yourself," she told him with a smile. "I don't want them to have to call me back to reign you in."