Sans lives alone, beacuse there is no Papyrus or Toriel to keep him company. One day, he saw a blue string. He followed it out of curiosity and found Error, who tried to kill him, but was saved by Ink. He left, and closed his eyes. When he opened them, he saw memories from the Undertale universe. When he got himself together, he began to build a machine to a place where everything is better.

This is the only way to actually kill UnderHell Sans.

  1. You'll have to Reset at least 3+ times.
  2. You have to kill everyone but don't go to the judgment hall in you last 2 resets.
  3. You have to be LV 23 (it is possible to do this because your LV stays the same even after resets).
  4. You have to find him which is hard because he is always moving.
  5. You have to "win" the fight before performing each reset (you can't really win yet because in each fight he has ketchup in his jacket so he doesn't really get hit).
  6. Once you have reset and "beat" him 3+ times you'll have to repeat steps 4 and 5.
  7. Once you find him in your 5th or 6th reset he'll be waiting for you in the ruins.
  8. Once you start the fight (again) you will notice that he looks more happy and pleased (the only reason he does is because you have been his only challenge since he killed Asgore).
  9. You finally beat him for real in this fight because after all the fights he had with you, he either ran out of ketchup or got so excited to fight you again that he forgot to pack it with him.
  10. Once you beat him you will be given LV23 to Lv50 and you will be given 10,000+ gold.

And that is how you kill UnderHell Sans.

Fun Facts

  • UnderHell Sans is the laziest of all the AU's and you can figure out why by checking out my other post but if you don't know why it's because he (unlike the other Sanses) works but not the way you think. His job involves killing other monsters that he finds unreliable. I thought I should also talk about Sans's Red eye. So Sans in Underhell as you've seen isn't very nice. His appearance can tell you that, but that's not all. Sans in Underhell is the main reason why there's a low population of monsters in the Underground. He also has a reputation for being incredibly powerful. This tends to go to his head. Because of this one day he sought out more power. He did this so that he could control his timeline. The reason why he wanted to control the timeline is so that he could possibly be able to reset or just get stronger. So on his quest for more power, he went to the True Lab while Alphys was out taking notes on Flowey. Sans took some Determination and used that to make him unpredictably strong. It worked but with unexpected consequences. He immediately began to melt and deform around his ribs and chest region. Eventually, it dialed down and the melting stopped. He eventually was able to get back on his feet and had Undyne make him a new jacket. However, she had run out of blue string so Sans would have to deal with the blood stained jacket he already had from when he killed half the population and from his accident with the black skeleton. So that's why he has a red jacket and a red eye.


  • Do you know if you cheat in Underhell your LV will drop to -20, your hp will be -20, and you will automatically be put in the Sans fight. So I ask you "Are you ready to have a Helluva time you dirty Hacker?".
  • Unlike Undertale Sans UnderHell Sans copes by turning his eyes off and looking more like a real skeleton. Also if you guys didn't know in UnderHell most characters don't show their eyes just like how Sans does because in this AU it magic is used to look good. Women don't do it because it's unladylike. For men, it doesn't really matter and Sans does to look scary which is all the time.
  • In my UnderHell fight when you first beat Sans it will actually take more than one hit to kill him because the first strike actually hits a ketchup bottle he brought with him just in case he failed. Also when he gets hit he strikes you with a gaster blaster killing you because you have 1Hp and then he leaves the judgment hall making you have to wonder around to find him again. UnderHell Sans doesn't believe in Sparing or Mercy. If he catches you sparing someone his opinion of you will change. If you kill someone or chose to do a Genocide route he will call you worthy or someone of interest. He will start to watch you as you kill everyone. Eventually, on some occasions, he'll even try to fight you. BUT DON'T FORGET WHERE THE TRUE BATTLE BEGINS!
  • In UnderHell Sans has the ability to travel between different timelines so if he isn't happy with what your choices are (sparring and using mercy) he could go to a completely different timeline. Example: If you were doing a Pacifist run he could just decide to not to be around all the sweet and nice feels so he would go to a genocide run timeline. In other words, he would go somewhere that (in his opinion) is more exciting.
  • Did you know Sans and Undyne in this AU are in love each other but there Pride and Ego's are so big that they are too shy to confess?

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