Undertale AUs and Sanscest rp!

Bad Sans Poly

Scenario 1:
Nightmare's gang are mortals. He is not. They will die, and he won't. After forming a relationship with them, it became an increasingly hard pill to swallow to the point where he would become inconsolable, retreating to his office to bury himself in work and research, trying to find a way for him to live.  
Eventually, he stumbles across a solution. One that they won't like, but they don't have to know. Reaper himself warns against it, but can't stop Nightmare from trading his immortality for someone else's lifespan.
The rules are simple:
Once the trade is made, the recipient will not die and he will live for however long the other would have lived and die the death they would have suffered. If, by chance, Nightmare gets into a fatal predicament before the lifespan is over, he will dust but sill be conscious in his ashy form, something that Reaper has described to be one of the worst deaths known to man and mosterkind.
He is more than willing to take that risk if that means he gets to live a normal life with his lovers. Not only this, but he can anonymously give his eternal life to Blue (whether the small skeleton likes it or not) so that Dream won't be stuck with just a soulless artist as a best friend for the rest of eternity.
Blue won't have to know why he suddenly feels more energized after opening his mysterious gift, he'll probably find some other explanation to his good bout of health. His lovers won't have to worry about his new weaknesses, he'll keep them hidden, figure out how to take care of his newly mortal form, and patch up any inevitably more harmful battle wounds by himself. And, lastly, he won't have to worry about watching his lovers disappear one by one.

Scenario 2:
Somehow, the gang manages to get to Nightmare, saying that he acts like a fossil and could never last a day attempting to be like them, or at least someone from their generation instead of the Jurassic period. Of course, Nightmare had tried to dismiss their ridiculous claims, but they wouldn't stop pestering him so he decided to put an end to it.
He stayed up nearly all night doing research, learning about memes, TikTok, and reddit. The amount of fandoms, youtubers, modern fashion, and slang he went through was mind numbing, and it goes without saying that all of this will be quite shocking to his gang the next morning (And hopefully put an end to their annoying mockery).Of course, he could predict that he would be tested, in a sense, expected to respond in certain ways. What he didn't foresee, however, was Cross inviting Epic over and forcing Nightmare into what is essentially a vine/meme war.
Does Nightmare know enough of this brain rot to come out victorious, or shall he be forced to admit defeat?

Scenario 3:
Whatever he was feeling was strange. Of course it couldn't be anything remotely positive. That would mean his soul is collapsing and he scoffs at the very idea of his death. Afterall, Nightmare is a god. A being who is incapable of feeling positive emotions due to the sheer amount of negative power he has. So why isn't he able to hurt them anymore? Why does he want them to be happy? Perhaps a part of him wants to watch them break again, or maybe he's unable or unwilling to acknowledge that he's falling down.

Alternatively, Dream could be experiencing true hate and grief. Unsure of what to do with these strangely strong emotions, he may end up hurting someone. It's not BSP but it felt wrong not to include it here too.

Scenario 4:
Essentially a chatfic roleplay where the poly is just sending each other lil messages except Nightmare will only send stuff like this:
Dear Cross,
I struggle to understand what the abbreviation 'X.D.' stands for and would greatly appreciate an explanation for something that you deem necessary to add at the end of nearly half your messages.
Much love, Nightmare
-
Killer,
While I understand that you are adamant I use the 'internet' to find answers to questions pertaining to the construction of digital messages, I find it much easier to simply ask you since I am much more confident in a sentient being's ability to retain and distribute knowledge. That being said, I would like you to provide me an explanation for the use of the symbols '8===D'.
With much love, Nightmare
(Btw 1 line rp responses ARE allowed for this specific scenario)

Scenario 5:
Create your own!!