There's no such thing as chalk anymore, as River knows perfectly well. At least, not where she and Simon come from. Not at the Academy. Not in that place where they'd... no chalk on the central planets. Not anymore.
Simon doesn't like it when she talks about things that don't exist. Simon takes care of her, so she doesn't upset him when she's lucid enough to comprehend. She likes to watch him with Kaylee. He's happiest with Kaylee, when they dance around each other like... particles of dust in the breeze. Like chalk dust. She tried explaining it to them once, but Kaylee looked frightened and Simon took her back to her bed and she knew they wouldn't be quite as happy anymore. Time to go, she thought and thinks, but there's no air. She can't be chalk dust with her big brother if there's no air to float on.
So she waits calmly for Jayne or Zoe or someone to walk past. She likes Zoe especially, because there's no pity in her. She's hard. River appreciates that. And sometimes they even talk, mostly about technology. But Zoe isn't very talkative these days.
River waits. That's usually when she starts drifting; is when they send her back to her quiet room. There's nothing to focus on. Her attention span won't let her stare at walls, even if she looks at a different one every few minutes and counts the cracks in the paint. She knows the numbers. She knows how long it's been since they were built. She knows which colours to mix to obtain that exact shade. But today she's going to make sure Simon and Kaylee know about chalk. About the softness and lightness and how it floats like magic and science, both together. Today's the day. They're going to let her in. She's going to show them she can behave.
And they're all going to float away together, away through space, and find somewhere safe. She can do it. She can show them.
She can.
She can.
Someday she'll know how to tell them about chalk dust.