Nightmare Blade - He has access to a sword made from Pure Negativity, which he can summon and de-summon at will.Ģnd Phase - Upon being damaged to nearly lethal levels, His eye will glow bright red, and initate a much stronger phase. Tendrils - He has access to Tendrils that come from his back, which he can use to attack his enemies Due to his lack of Empathy, he generally not care what he does to you, no matter how cruel or disgusting. While he generally doesn't talk much, other than orders, or some sort of speech, he does often make others fearful. He almost always has a Sadistic Smile on his face. He normally has something of a slow stumble rather than a walk. Sometimes a small white pupil is in it, however it is rare. Rather than having a glowing blue eye all the time, his eye is normally pitch black. However unlike Error, his clothes are filled with stains. Turning into a Cold Engine of Destruction. Then he allied with him against The Protectors. Eventually he was defeated by Error, and Error took over. After Error manipulated him in his Dreams, he eventually formed a small faction of villains. After Dream escaped, Nightmare fled the AU. Blaming Dream for all his failures, he attempted to murder Dream, finally reaching 50% Corruption. when he woke up, he assumed he had killed them. Eventually, Nightmare snapped and almost killed Nightmare!Chara and Nightmare!Papyrus, from hallucinating, due to being half asleep. Due to their hatred towards the Common folk. Eventually, The Corruption that had started at 5% on the nightmares began growing. The Common folk began constantly attacking Nightmares, normally ending in deaths. As they were the guardians, and occasionally the cause of Negativity. The common folk eventually directed all their problems to the Nightmares. However, eventually Dream got overly popular with the common folk. This pattern continued until everyone who had died from each AUs' respective genocide routes, was now alive again. Eventually, he was able to describe his brother enough that The Spirit of Positivity made a replica, Dream!Papyrus. Eventually, The Spirit of Negativity heard about this, and used one of it's apples to make a replica.
However, one time while he was talking to Chara about Papyrus, he began to forget more and more about *how* papyrus died. Dream was happy to see new people, and Nightmare was just happy to have someone to talk to. They became Nightmare!Chara, and Dream!Frisk. Chara ate from the tree of Negativity, and Frisk from the tree of positivity. As it seemed, Undertale Chara and Underswap Frisk had been reincarnated, but without memory of the past events. Eventually, two albeit familiar humans came to the trees. Nightmare was generally more antisocial, due to not only his intimidating appearance, but also surplus amounts of negativity. After Five years, the two had a decent friendship. And since they both had nothing better to do, they obliged. The Spirits explained how the two were now guardians of each respective trees. After the humans died, they were encountered by the spirits of each tree.
Nightmare and Dream successfully were able to kill the humans permanently. This turned Distrust Sans into Dream!Sans, and Undertale Sans into Nightmare!Sans. Distrust Sans ate from the tree with the yellow apples, and Undertale Sans from the tree with The Black Apples. The other, Purple leaves and black apples. One of them had blue leaves, and yellow apples growing from it. After continous fighting, They reached a strange location in an alternate universe they didn't recognize. The Humans eventually struck down Undertale Asgore and Underswap Toriel. After constant fighting, they fled to different locations. (E.G., Underswap Disbelief.) The two of them teamed up to stop their respective humans. Somehow through his research, he encountered an alternate universe version of himself. Nightmare Sans was originally just an Undertale Sans from a Genocide route.