So , if this is still Frisk with a new look and name that we are talking about (after they died by falling the wrong way on the flowerbed I guess) , it would make sense why they would want to completely forget and change themselves and their past...
I still don’t think it’s Frisk as the soul is the wrong color, and Frisk was gone when Fae and Toriel came back. I don’t think Flowey has any reason to drag off the body, so Frisk probably got up and left
Wait, I just realized, is that glasses girl...crying? And Fae is saying it's her fault and she's sorry, so I'm not sure what's happening here.
All I know is that it was triggered by Papyrus grabbing her hand out of enthusiasm, presumably pretty hard, so ouch.
But the thing that set her off was the combination of Papyrus taking her hand and saying welcome.
Papyrus did grab her hand gently, though.