#just a semisentient bit of consciousness that remembers that he and sans are buds and not a lot else

[hahanoiwont]

@candy-cryptid yes! That's another bit of evidence that I forgot to add--"man" implies that his gender is known, which can't necessarily be said of the player; so we know (or can assume) that there is a man from another world, and we know that Sans refers to wanting to go "back" somewhere, but being unable to, and instead accepting the underground as his home.

Also, "beware" makes sense in this context, too--since Sans is able and in some cases willing to deliver a whooping for the ages. I think by raw power alone, Sans is worth a "beware" or two. So that line could refer to him!

I want more of your Undertale headcannons. SPILL!!!!

Alright! Any specific kind? no? here's a thing:

I think Sans Undertale is from an alternate dimension. I do not think he is from the Underground at all.

This is for a variety of reasons, mostly hints: the riverperson's "beware the man from the other world" line, Sans's lines concerning the Surface ("we call that the sun, my friend"--who's we? presumably people who experience the sun and therefore have a reason to call it anything), and most of all Sans's frequent references to wanting to "go back"/accepting he can't "go back."

Now, going back could refer to time (ie my "what if Sans used to be able to reset" post), but I believe he means going to a physically different place. The vagueness of "going back" could be an attempt to make his experiences more understandable from a time-travel perspective, or just because he's mostly speaking to himself, but the most obvious interpretation is that he was in one place, ended up in another, and has since been unable to return. Occam's razor.

Similarly, the restaurant conversation could be interpreted as personal experience--his argument is basically that the Underground might not be what Frisk is used to, and it might not have everything, but it may not be worth it to try to return from the world they're from. Sometimes you have to learn to settle. Which seems more like an argument that comes from a place of experience/empathy than something he sat down and though would be the most convincing logical argument to use for them, especially given what he knows about their determination. They absolutely can kill Asgore and cross the Barrier, or perhaps find another way...but maybe, like him, they'll find that they're happier just accepting where they are and building a better life Underground, rather than struggle to reach their old home, only to realize that the cost is too great. Especially because he doesn't know why Frisk came to Ebott in the first place.

There's also the issue where no one seems to know where Sans and Papyrus come from. The people of Snowdin say they just appeared one day. Papyrus similarly just appeared outside of Undyne's door one night. Sans has science stuff and pictures of him with several mysterious figures in his secret lab basement thing--could be a connection with Gaster and the Gaster Followers, and/or items he has left over from another life in another world.

Anyway, it's not proof positive that he's from an AU (Deltarune...?), but it's a fun idea to play with! And, ultimately, it makes a lot of things about Sans make sense. Now the real question becomes, where did Papyrus come from...