UnderRESETTale is an AU created by SomePersonsAccount. It is mainly about RESET!Sans & each of the humans that fell underground.
About the AU
UnderRESETTale is an AU where Sans has the power to RESET, SAVE and LOAD, and he knows everything that goes on in this AU. He's basically the lord of this AU. However, he RESET the timeline so many times that he lost his sense of reality and went crazy with power. Every time he RESET, he found that his ability to RESET spans over a longer period of time, and he can time travel backwards, as long as he remembers exactly what happens, or else what he remembers will play out rather than what happens exactly. Sans still wanted more power, so he RESET back to the points where each human fell underground, eliminating each of them, and exterminating monsters that refused to listen to him, increasing his LV, then he reset, doing it all over again. Papyrus in this AU is still Sans's brother, and he follows Sans not because he wants to, but out of fear, following each of his orders. He is afraid of what Reset!Sans is capable of.
In this AU, there are several different timelines.
Timeline I is the timeline where RESET!Sans first used his power to RESET. At this point, Sans is sane and didn't do anything bad yet. He remained in this timeline each time he RESET, until he lost his sense of reality, then he RESET way back to when Chara was in the underground.
In Timeline II, RESET!Sans and RESET!Papyrus reset all the way back to the point where Chara was in the underground, SAVEd, and then eliminated them. Then he waited, and did the same to the other humans that fell underground, and some monsters who refused to follow him. This is basically the really bad timeline.
In this timeline, Sans & Papyrus LOADed his save file back when he eliminated Chara, but he found out that Frisk fell underground instead of Chara, so he tried another RESET to try to eliminate Frisk from existence, but this made it worse for him.
Timelines IV-Timeline X
In Timeline IV, Sans & Papyrus RESET when Sans found out that Frisk was alive, but he found that not only Frisk fell underground, but 20 minutes apart from eachother, the human he eliminated that had the yellow soul, Justice, fell underground also. From then on, each time him and Papyrus RESET when things didn't go his way, one human was added into the underground, making their job much harder.