You did Genocide Route (or not), you killed every Monsters, such as Papyrus, Alphys and Undyne... So you are now in the Judgement Hall, meeting the Bad Time Trio & the Mad Time Trio...

As you meet the Trios, you saw one of of the Trios that you recognized... Sans, Swap!Papyrus and StoryShift!Chara.

Sans: Well, who do we have here?

Swap!Papyrus was smoking a cigarette.

StoryShift!Chara: Pap, stop smoking, it's dangerous.

Murder!Sans: sigh Someone's in big trouble...