Halfway to the sofa, they stopped, making a small sound like a grumble of annoyance. For a second, the red glow in their eye grew faint. "Sleep," they rasped out in a low, halting whisper, "I saved you an ache in the neck." It took him a second to register that the kid wasn't talking to him. Mostly 'cause Frisk didn't speak. To him. Or ever.

Sans wakes up late into the night and sees something he shouldn't have.