
You could get the sh*t beat out of you if you so much as look a guy wrong. And when you live in a world where its ‘Kill or be Killed’, it’s difficult as hell to find something to be happy about when you can be backstabbed, robbed, betrayed, among many other awful things at any given point. All their innocence as children is fading away and they’re seeing just how cruel the world can be. This is why this usually happens when a monster is somewhere within their teen years or as a young adult. What REALLY happens is that the monster’s spirit was crushed and their hope is lost. When a monster’s eyes turned red- which typically tended to happen as an adolescent- it meant they were maturing and growing up. In the UF Universe, this was seen as a sign of maturity. UF Papyrus had orange eyes like UT Papyrus.īut at one point or another, their eyes would change to red. Our headcanon is that all the monsters, every one of them, actually had the same colored eyes as the ‘original’ characters from Undertale when they were born and grew up. BUT! We decided to have a reason as to why that is, and thus the theory was born. Monsters in the UF world all typically have red eyes, or near it, and their magic tends to center around red.

I believe this is where the confusion began because it was only really discussed from the perspective of Sans- AKA Edgy- and the diagram centered on him, which you can find here. The theory involves the red eyes and ‘magic’ of the Underfell Universe and was originated between and I. So let’s begin! First, What is the Red-Eye Theory? So I’m going to be as thorough as I can, and if you have any questions, PLEASE do not hesitate to ask! Okay, SO! There’s a lot of confusion when it comes to this theory, and people do not seem to understand how it works exactly.
