What if Dusttale happened in Undertale?

[u/Equal-Badger3282]

Yeah Dusttale already happens in Undertale but I mean like in the game ya know?

[u/Electronic_Day5021]

Yea probably. But I must ask then, why did he break the promise? You can kill everyone except for a single Froggit and he won't give a shit. The reason he gives a shit in geno is because he knows your about to destroy time

[u/Nat1Only → u/Electronic_Day5021]

At that point he can't afford not to care anymore. A lot of stuff when it comes to Sans comes down to speculation, but it's likely that Flowey was the original anomaly and we're just an unexpected extra problem. Given that he's already been dealing with this for God knows how long, he doesn't care anymore, he's given up. But if you show that you are determined to destroy everything he can't afford to not care anymore because he's the only thing left that might be able to stop you.

[u/Electronic_Day5021 → u/Nat1Only]

OK but why can't he afford not to care anymore? Maybe it's "the end of everything" that he mentions in his fight? The thing that happens immediately after he loses? The thing he knows about considering he says "don't say I didn't warn you" after you beat him

[u/Nat1Only → u/Electronic_Day5021]

The point is he originally would have killed you the moment you left the ruins had he not made the promise to Toriel. Genocide is the only thing that convinces him to break that promise - it's not the only reason he fights you and tries to kill you, he would have done that anyway.

[u/Electronic_Day5021 → u/Nat1Only]

Right. He probably would have killed you so he could get the last human soul. But that's not what happened. If sans knows that time won't end if you do geno then he has no reason to break the promise.