In this story, it was prophesied that one of the brothers are gonna turn to the evil side. Dream strongly believes that he will never turn to the dark side and that Nightmare is the one who will. He boasted that he's the good guy and evil will never take over him even to the point of eating one of the the black apples to prove it.
So, in this alternate reality, Dream's personality involves being overly-confident and prideful, he thinks so lowly about his brother and always assumed that Nightmare was and always will be up to no good. Nightmare, on the other hand, is humble and kind-hearted. He's actually proud to be the protector of the bad side of the Tree despite what most thinks of him. He always thinks of it as his special purpose rather than a curse.
I think they will get along with Template and Pale XD XD I mean if Ink has Dream and Error has Nightmare(I dont mean shipping, like a partner in crime or smth). Why not Swap!Nightmare with Template and Swap!Dream with Pale? XD
Hmmm...now that I think of it
I dont have a special name for Swap!Nightmare and Swap!Dream
I mean, I thought of some for Swap!Dream, it's "Delusion" or "Pipe!Dream". But it doesnt seem to be good enough yet
Could ya guys suggest a name? That'll be great! XD
Undertale (c) TobyFox
Dream!Sans & Nightmare!Sans (c) Jokublog
Swap!Nightmare and Swap!Dream concept (c) Me