(It is perfectly okay to add your own fanart to the pages.)
Some info is that instead of being a yellow flower, Flowey is a Poinsettia, Frisk and Chara have genders(i.e. Female and Male), Frisk and Chara are Mages.
Instead of the normal white battle armor, Papyrus has spikes on his shoulders that fade into white.
Instead of his blue magic eye, Sans has a indigo eye with a yellow crescent moon on his left eye socket, along with a circle pattern that is indigo on the top of his left hand.
Arial, (The skelebros mother) exists in this timeline.
Sans has the knowledge of the Anti-void and Guardians, not even Error realizes this.
Mettaton has a sidekick known as Elainbot.