*Have you thought about a world where everything is exactly the same...
*Except you don't exist?

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Underdecay is a world where the constant resets actually start to affect not only the characters, but HOME itself. No matter the path, kindness or violence, every reset leaves a permanent mark against the new timeline, similar to a scar that never fades.

Each reset leaves a small impression on the monsters that interact with the fallen human, the result of which becomes more and more prevalent with each new reset. The monsters are slowly becoming more aware about living the same life over and over as moments of deja vu and unexplained intuition seep into their lives. The past royal scientist took it upon himself to try to mitigate the damage caused by perpetual resets and for the most part actually succeeded but in his absence, the world slowly falls into decay.


Major Characters


  • He enjoy exploring his new playground and discover the new anomalies around the underground.
  • He’s not a threat to monsters anymore.
  • He actually attempt to stop the fallen human from making true reset by using the 6 humans souls.
  • He get along with Sans.


  • She’s the main character that died the most.
  • She turns to dust a few hours after the resets.
  • She doesn’t react to outside stimulus anymore.
  • Decay!Sans is aware of her state.


  • He’s keeping himself isolated from most monsters.
  • He mostly stay at his home listening to music.
  • He keep crying no matter what.


  • New stimulus confuse him and makes him anxious.
  • The growing anxiety and worry with each reset starts to affect his decisions and his reaction as well.
  • He’s scared of physical contact (due to having been killed a few times) and doesn’t talk very much except if he need to. (Like many, he bottles himself up.)
  • When relaxed, he’s pretty close to the Sans we all know (especially when it comes to bad puns!).
  • His eye change color from yellow to cyan depending on his mood.


  • Papyrus seems like he still have his positive attitude.
  • He remember partially resets and see them as déjà-vu and livid dreams.
  • He feel confused when things are not where it’s supposed to be causing him lots of stress every times something is out of place.


  • She’s more violent and aggressive then she used to be.
  • Her magic is pretty much unstable and tend to turns partially against her.
  • You can’t befriend her anymore.
  • She’s determined to gather the last human soul at all cost.
  • She encourage other monsters to do the same as well, but work on her own.


  • She’s cold and calculate.
  • She prefer spend her time in her personal laboratory to focus on what’s matter the most. Her DT experiments.
  • For the greater good of all monster kind.


  • Like UT!Mettaton, the metal part of his body is extremely durable making it hard to take him down.
  • The screen and the soul container is however damaged making it hard for him to coordinate his body properly.
  • Mettaton’s vision is slightly damaged, but he have been used to it.
  • His main goal is to stop the fallen human and gather their soul at all cost.


  • He lost his willing to fight the fallen human.
  • He try to reason him rather to attempt taking his soul.
  • He’s eaten by guilt.
  • He doesn’t take care of his plants anymore.


  • He doesn’t want Chara to keep playing anymore.
  • He try to gather the fallen human soul to free everyone.
  • Asriel is an important ally to the inhabitant of home.

Minor Characters



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