[Papyrus nods at the instruction about stopping if he wants, and keeps some of his attention on his own comfort with the situation. The delay isn't a reason to stop, but it's enough for him to wonder whether anything's going to happen. The initial mild happiness is easily mistaken for relief nothing's going wrong.

Then the flood starts. His lingering concern, doubt, unease, even the irritation over the knife are overwhelmed by happiness as his system tries to process the emotion with the available functionality. After the relative numbness of the last several days, it's a boggling intensity - but it's not enough to process everything of the external command to feel happy pressing on him.

It's just as well Papyrus isn't gripping Sans's hand - his hands clench tightly as internal errors flare up like a wave of pain, until the existing directive to record everything gives way. The confrontation with Hannibal, the rude men on the street, the moment of paranoia when he first discovered a text in which Sans addressed him as bro... As the ongoing emotion processing abruptly shifts to the current happiness, the memories fragment and corrupt with random errors. Papyrus starts to laugh.]

I don't... Nyeh heh heh, I don't remember everything, I don't... I don't remember exactly what your face looked like, a few seconds ago! [It's not overwhelming happiness anymore, nor hysterical laughter. It's funny, now that it's happened, what a relief it is not to be remembering those things so vividly. It's disconcerting, alarming, scary to have parts of his mind just up and disappear - but it's hardly the first time that's happened. There's other emotions starting to fill in the spaces that were left in stasis so long, with the happiness is taking center stage, framing his reactions to everything happening. He slouches back against the couch, still grinning to himself.]