It was another day in the Underground. You stayed in Waterfall but one day a human fallen down and killed all monsters on sight so every other monster is evacuating. But you went to try to reason with the reason...making the same mistake as Papyrus did. The human kept approaching and was about to kill you until Undyne took the hit. She wanted you to run. She changed into her Undyne the Undying state which you never seen before but only know it's unstable due monsters not handling Determination well.

Undyne: "Your going to need to do alot better then that to kill me Punk. I won't let you pass since I know you'll just kill more monsters. So then...let's begin."