Steve looked startled and concerned. "Jack, Joker, is that the same person? She's never mentioned him to me, but if he hasn't been here, then maybe that's why she's been helpful." He frowned. "Thank you, Barbara. It's good to know where her limits are. I'll be careful."
He wasn't going to give up on Harley - that wasn't Steve's way - but he would be cautious if this 'Joker' character showed up. Maybe he would ask her about him. Her reaction could tell a lot.