No... My body... It feels like it's splitting apart... Like any instant... I'll shatter in to a million pieces. But... Deep, deep in my soul. There is a burning feeling I can't describe. A burning feeling that WON'T let me die.This isn't just about monsters anymore is it? If you get past me, you'll... Destroy them all won't you? Humans... Monsters... Everyone... Everyone's hopes. Everyone's dreams. Vanquished in an instant. But I WON'T let you do that. 
Right now everyone in the world... I feel their hearts beating as one. And we all have ONE goal. To defeat YOU. Human. No WHATEVER you are. I, UNDYNE will strike you down. You're gonna have to try harder than THAT.

No, you know what? SCREW IT! WHY SHOULD I TELL YOU THAT STORY WHEN YOU'RE ABOUT TO DIE!?! NGAAAAAHHHHHHHHHHHHHHHHH!