By just going off of the other woman's accent, Joan was thinking she was Eastern European, most likely Russian, but she wasn't about to point that out. Not when there was obviously more pressing issues at hand. Such as this Lucifer thing and her suddenly being halfway across the country from where she'd been just minutes before. And to top it all off, she was seemingly in another dimension of some sort. So while Joan was aware of some scientific theories about parallel dimensions and such, she'd seen a couple documentaries in passing, she'd never really given the theories much thought. Now it seems she probably should have because such knowledge may have prepared her for this.
"So okay. Lucifer is real here and fairly certain it means we're all in trouble. Also judging from what you've told me, there seems to be many people here from other places. So is there some sort of base of operation?"
Joan was doing well and going along with the flow. Yes she thought this was completely insane sounding, but obviously there had been something that had instantly transported her halfway across the country. So really, she could go along with this explanation for now. Though Joan was more the type to not believe it until she saw proof, but there was undoubtedly proof yet to come. Or at least she hoped because right now she was banking on the fact this was real and that sherlock hadn't shot her up with something.
"Wait, popular culture? Like characters from books and so forth?" Now this only further enhanced Joan's skepticism and her arms remained crossed. She was going to need some sort of solid proof soon because she could only go along with this train of thought for so long before she started pointedly questioning it.