The smile doesn't falter. All Mettaton does is wave to him before turning back to Frisk.

He's the host, of course he's seen Pitch around, he knows everything that goes on in his household. He came in with Frisk, and he hasn't socialized much; maybe he's shy. Mettaton won't force him forward, especially if he has no act ready.

"All the dogs are around the back now, sweetheart, playing cards. They'll be the easiest to visit. But first, would you like to preform an act with me for old times' sake?" Smile, smile.

Frisk glances back and shakes their head. "No thanks." They have Pitch to do stuff with right now. "Maybe later."