Nightmareswap is set four-years post pacifist route; where the monsters live upon the surface with monsters happily. Chara lives with Asgore, papyrus and sans . All is well, however, happiness does not last. Over the course of few weeks, Chara had been experiencing traumatic nightmares of their preview genocide route in the previous timelines. The nightmares progressively get worse and they (Chara) learns that the nightmares are influenced by Frisk and their 'magic'. Chara therefore, begins to experience post-traumatic symptoms of the memories of the genocide route (both from their own actions and their judgement from papyrus). papyrus learns the nightmares are initiated by Frisk when their powerful enough to manipulate Chara's physical actions. He and Chara begin to look for answers as to how and why this is happening. In this emotional journey, Chara has to confront their past actions, and Frisk, for the sake of their families safety.
- The prologue is set in the original story of Underswap but with a few additions.
- Chara (and frisk) had made 94 attempts in pacifist timelines. This is because they are in search for different outcomes (or to see if they missed something) to try and save Monster kid.
- With the continued search to try and save Monster kid, they began to explore whether the killing of some monsters would change the outcome. However, as we know, this only lead to misfortune and not a pacifist ending.
- After 3 different neutral endings, the outcome was still the same - MK could not be saved.
- This constant failure caused Frisk to anger, and in a final attempt, Chara and Frisk resettled, and committed a genocide run to see whether the monsters sacrifice would cause an outcome to change. It did not.
- Frisk became enraged. They made a 99th reset, but this time, it was only filled with Frisk's rage. How the monsters did not help save Monster kid so many years ago.
- However, they not able to complete the entire genocide run a second time. In their fight against papyrus in the Judgement hall, Frisk had tried to fight him.
- But Chara could no longer withstand the physical and psychological agony of harming their friends and family. They took action and spared Papyrus. And of course, Papyrus killed them.
-Chara told papyrus why they had done all of this. And placed the blame on Frisk and themselves. And before papyrus could say anything, Chara killed themselves, and made a reset for the 100th time and completed a final pacifist timeline.
- Frisk was nowhere in sight of this final pacifist run.#
- In this final pacifist run, Chara unfortunately was still unable to save monster kid. As much as MK/Temmie continued to tell Chara to reset their memories after each run, he clearly still had some recognition of the multiple resets. Monster kid told Chara to stop and that it was time to let go. Even though Chara stayed with him for a long while, Monster kid continued to tell him to go. And sadly, Chara did.