[The small, encouraging smile that they'd been holding cracks a little when Asriel trails off. That's...that's right. If he's himself again, that means he doesn't have the soul this place gave him anymore. He might change again, become bitter and hateful and unloving all over again.]

[No wonder he ran away.]

Maybe...maybe you won't? We didn't know how long it was gonna take before, an'...an' I talked to someone about this stuff happenin' a little while ago. He said it just lasts a few days, then everything's back how it was.

[Frisk's hands squeeze around Asriel's paws (paws just like Asgore's and Toriel's, but so much smaller, they don't swallow up Frisk's hands like theirs do), and they kick up the confidence in their smile by a few notches.]

So...so maybe it won't happen!