It's Chara-like enough to make him pause. They felt comfortable enough to borrow his bed, before they disappeared, and he... aches for them. The silly little child, calling him 'nerd' and 'educating' him on those poorly drawn comics that are such a fad these days. Their reading and writing lessons, him drawing for them and encouraging them to fill in the speech bubbles. And the octopus toy he gave them, which they went on to carry around constantly.

He misses them.

So, he stands up with only a little difficulty and says nothing. Let him be really mute for a moment. He doesn't understand what their concerns are, or maybe he's just tired, because he doesn't know what to say.

But he can go to tuck them in. That's enough.