ERROR MIGHT WANT TO ACTUALLY FIGHT SOME FRISKS. Fortunately, he'd still be mostly limited in power because it's still Serif's body.

(Undertale!Sans had also pretty long ago lost track of "which" Sans he was, in terms of backstory before the resets happened. Gaster being briefly in the castle helped sort him out. So he would sympathize a lot with Frisk there ;-; These things happen, yep.)

I'll be especially interested in how Storyshift!Sans reacts to Flowey - "you're really kinda grouchy, aren't you?"