When Leah heard the news from O'Brien that his sister and nephew were in quarantine, many reactions had vied for attention, and she was grateful the man hadn't been around to witness them. Then again, given the relative silence of their trip to Grand Central, perhaps O'Brien wouldn't even have noticed her anxiety or doubt. Anxiety, not only for the reason his family was in quarantine, but for the brief fear that she might lose him because of their reappearance. This wasn't about her, though. Not in the least.
So when O'Brien shoved his way into the area where his sister and nephew were sequestered, Leah stayed nearby long enough to make sure the guards weren't about to kick him out. After that it was a matter of deciding what to do next. Should she wait? He'd stuck around for her (well, for Lilah, mostly) while Kori had been in quarantine. He knew Kori, though. They were something like friends. This sister and nephew? Leah didn't know them. To them, she was a stranger.
Besides that, she didn't know how long O'Brien would be staying in there. A few minutes, a few hours. Maybe even the whole week. Leah couldn't realistically remain out here in the waiting area for that long. She had things that needed doing. An hour. She'd wait an hour, give the family a chance to catch up. If O'Brien didn't care if she stayed or left, then she'd take that as her cue to leave. While her intent was to be supportive, Leah didn't want to be that clingy... not-quite-girlfriend person that wouldn't leave him alone in times of crisis.
Pacing always helped to pass the time, and that's what she did up until she heard the door creak open. Leah spun around toward the sound, eyebrows raised expectantly.