you walk through Snowdin, you see how a Sans who has just come out of a portal, approaches another who was standing confused to see another one just like him

[Murder-Sans] looking at Insanity-Sans "The hell...? Why do you look familiar...?"

[Insanity-Sans] looking at Murder-Sans, I have the skull of the Papyrus of my universe in my hand "Why? Well, let's just say that... I'M THE MANIAC YOU SHOULD RUN FROM =)"

Murder-Sans and Insanity-Sans were about to fight but they stop when they notice your presence

[Murder-Sans] looking at the third comer "Full shit! I'm not ready yet! I still don't have enough LV, I haven't killed enough monsters "

[Insanity-Sans] talking to Murder-Sans "What's wrong? Did that little turd scare you? I must admit, I thought you were better than that!"

[Murder-Sans] talking to Insanity-Sans "Don't you understand?This "little idiot" is the only reason why I became a murderer, I became one killing machine to put out another! I'm offering you a deal! If you help me kill the human I keep you alive! What you say to that?"

[Insanity-Sans] talking to Murder-Sans "I'rll say: 'You're idiot'! If you survive and you don't fight against me... I'll just kill you! You're not in a position to make deals right now!" with a psychopathic smile "Kill or be killed! Everything that comes my way dies"

[Murder-Sans] talking to Insanity-Sans It's clear to me when I see Papyrus's skull in your hands, believe me, after this I'll kill you. Like a team!"

[Insanity-Sans] talking to Murder-Sans "Well, that seems fair to me"

[Murder-Sans] talking to Insanity-Sans "Are you sure we haven't met before?"

[Insanity-Sans] talking to Murder-Sans "Enough of this chatter! GO AHEAD!"

Insanity-Sans and Murder-Sans summon Gasters Blasters and bones surrounding you