I actually have two
1. After a true pacifist ending Frisk is revisiting the underground one more time only to find Asruel in Snowdin and under investigation from Alphys she figures out he now has a soul made up of small pieces from every monster due to having absorbed their souls
2. After a true Genocide ending Frisk gets out of the underground and visits the place where she and Toriel would have lived in and has an emotional outburst releasing so much DT that it makes a pocket reality and a weird one where she’s an adult and Chara and Asriel are her adopted kids and she had her friends but it’s a bit strange
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