Random Killermare and Colordream (My Main AU because personalities)
Nightmare and Color do not like each other.
Nightmare wants Killer for himself and doesn't want Color around, in fear that he'll steal him.
Color likes Killer and wants to help fix his soul. He thinks Nightmare is manipulating him and is trying to find a way to "save" Killer.
Killer willingly chooses to date Nightmare, even after his soul is fixed.
Color still thinks that Nightmare is manipulating him and asks Dream for help.
Dream knows that Color doesn't know that he and Nightmare are siblings and suggests they date to piss off the Guardian of Negativity.
Ragebait successful, and Nightmare is now more pissed off than ever when he sees Color dating his brother.
Color thinks Nightmare is just upset that he has the Guardian of Positivity as his boyfriend.
Dream told Killer about it, and he and Killer are just giggling at the situation. (Driller as best friends lol)
Color and Dream actually fall in love and date for real in the end.
