Okay so like all things that have been featured on-screen in this world, i have a theory about the Underground.
I was browsing through the Undertale wiki and while reading the article page for Frisk (the character you play as throughout the game), I saw this in the trivia section:
Frisk's Trivia wrote:It is possible that Frisk falling into the Underground was an attempt of suicide, though this is only hinted at, because of the conversation where Frisk was asked why did they climb the mountain: "Was it foolishness? Was it fate? Or was it... because you...? Well. Only you know the answer, don't you..?"
That got me thinking, what if Frisk
did manage to end his/her life and falling down the hole into the Underground was a representation of ascending to a Limbo-like place (the bed of flowers Frisk wakes up in could maybe represent them waking up as a spirit) as a spirit where they will be judged for their actions and to see if they will get a chance to be rebirthed (going back to the surface) or be sent to Heaven or Hell. To me, the spirit, being represented by Frisk, wants so badly to be rebirthed that they face each trial they are given with one big goul: to be able to returned to the surface world. It also may depend on the three seperate routes you take in the game, Genocide, Pacifist or the Neutral Routes. The Genocide Route probably means the spirit is restless and will do anything they can to reach the surface world to take revenge or similiar (thus, "enslaving humanity").The harder boss battles in this mode, such as Bad Time Sans and Undyn the Undying, represent the guardians sne tot prevent you from doing so. The Pacifist Route represents the spirit doing anything they can to get into Heaven so they can rest peacefully, avoiding any conflict (sparing everyone or fleeing in each game battle phase). The Neutral Route could probably represent the spirit being rebirthed, dying again, meeting the Devil (aka Flowey) who lets the spirit
anotherseries of trials to try the two other routes.
Yeah, that's it. I hope no one is offended about me talking about this cute, adorable game like this. It's really just a random speculation I came up with on a whim. In all honesty, I love this game and it's story.
