Ok so my friend Lazynouguy is making a new au and I've been thinking if making one for a while do here's the idea:

The au would be called Yantale. Basically you play as Frisk and you go through the underground making friends with everyone. The side characters don't really matter too much in this it's just how you treat them. Depending on the way you treat characters will depend on how the boss will treat you. For example, if you're overly nice to people in snowdin, Papyrus will think that you're not focusing enough on HIM, since all the boss characters are yanderes, and will only attack to prove he's better than them. If you kill them, the bosses think you've killed for them and will spare you unless it's Sans who isn't a yandere and sees past your facade.

Just realised that this sounded better in my head then when I write it xD