my opinion and nothing you say about the others can change it

yes

Actually, Toriel was the 1st to ever get a AU which started with Underfell. Sans was the 2nd. that's what started the AU's all of a sudden.

but sans made it popular. whats the first thing you think of when you think about an au? probably the sans

True, sans did make it popular, that's why no one gives credit for the person who made Underfell Toriel in the 1st place, because everyone thinks it was Sans who started the whole AU thing. but my mind usually goes to either Sans OR Paps.

SANSTALE

true

yes