So here's the run down. In Undertale's Genocide Route we are introduced to an evil being named Chara. In ResetTale Chara actually has a conscience. In Chara's run when they fall down and meet Toriel their first reaction was to kill Toriel, but since they felt guilty and used the power of their sould to go back to before they killed Toriel, but that was when Chara's eyes could do the melty thing, but Toriel's colours were...altered, like Toriel wears purple and white but after the reset she wears black and orange. The next time was when Chara met some of the Ruins monsters. They had no idea why they were killing all the mosters but everytime they did they would Reset and all the colours of that Monster would alter. It's all the same, even with Asriel and Asgore. Asgore's colours were the same as Toriels but Asriel had a Dark Purple and Dark Green Sweater. Now skip to when Chara gets sick. In this Universe, when Chara got sick it was because they kept Using their powers to bring back the dead monsters and when they died and Asriel absorbed Chara's soul he reset and Chara's sweater changed to match Asriels...but sadly Chara did not reset and when the Human's killed Asriel Toriel pledged that all human's that had the power to reset like Chara would be eliminated. but when Frisk fell, she couldn't help but protect the young human.