[The smack is only a surprise in the exact timing and location, but less impactful than he'd been bracing for, so he lets it go without complaint. There's more important things, like nodding and continuing to try grounding him.]
If... you want, to slee-p. I'll keep wa-tch.
[There's reasons why he sometimes wants Sans to read him stories before he sleeps, after all. It feels safer, knowing his brother's there and safe. Like it reassures some deep worry about his family disappearing, that otherwise leads to nightmares. But there's not much point to thinking about it.]
what are couches for if not sitting and having feelings, then taking a nap
If... you want, to slee-p. I'll keep wa-tch.
[There's reasons why he sometimes wants Sans to read him stories before he sleeps, after all. It feels safer, knowing his brother's there and safe. Like it reassures some deep worry about his family disappearing, that otherwise leads to nightmares.
But there's not much point to thinking about it.]