[Right. Sarcasm undetected. Which tells her Dash believes the whole we're-stuck-here-but-it's-not-a-locked-hospital-ward.

Actually, she's starting to have to face that possibility herself. She is talking to a rather colorful pony right now, for example.]

Wait. As much as we don't always get along, my sister is still my sister. Are you saying she might just... vanish from here? [She knows that, or at least has heard it before, but... she hadn't thought of people leaving before her. Not people she'd actually feel a bit lost without.]