There's one last transmission, "Coming, said I'd find you I said. I was looking I looked," before it dissolves into breathing hard as she runs. River can't remember how to get to the room, but she can feel her brother. Little pings of worryworrybrothersisterworryconfusedcleanpressedSimonSimonSimon that she follows like radar until she sees him and can't decide to smile or cry.

Because he's right there all real and solid and a person and she'd looked and she couldn't make him but he's there anyway and it's been so long...

"Simon?"

Ignore the hitch in her voice as she stands there and stares like he isn't real, but she has to make sure because she doesn't know if she really knows. If someone can steal Inara then they could steal Simon, and River hates this place for making her not know what she ought to.