You know something I was thinking about the other day in regard to the other world sans theory, you know how the newsletter hinted at papyrus also being from another world?
It got me thinking about neutral runs, and why Sans's mental stability is affected so much by whether papyrus is alive or not, like even if everyone else is dead, he's pretty chill as long as papyrus is around, and even if everyone else is alive, he's pretty pissed even if you ONLY killed papyrus.
Now that could just be because papyrus is his brother, having close family around can help with that kind of stuff, and losing them would hurt really bad, especially if you actually spared some people, implying that you had mercy in your heart, you just didn't spare any for papyrus, a beacon of kindness who literally can't even kill you, unlike other monsters, which you presumably spared.
But like, sans is a VERY social guy, he has a lot of friends, and thus a lot of emotional support, you'd think a guy like that would more chill about this, especially considering the number of things he lets you get away with before stepping in, but all it takes papyrus to die for sans mental health to go down drastically.
But that's just it, what if these emotional support pillars called friends and colleagues, ARNT as stable as they should be? What if papyrus was the strongest pillar holding it all together? This is where I get back on topic to the otherworld sans theory.
You see, if sans ISNT from this world, then his connections to the people around him are lot more superficial then they might seem on a first glance, sure he cares about these people, but to him, a lot of them are people he already knew, people he already knew how to make laugh, how to make comfortable, how to be cool with, while they have very little knowledge about him.
In other words, these relationships are very one sided, sans already know how to befriend them, while they like sans for presumably accommodating them without him even having to try, they didn't actually have to go through the process of making a relationship, and could skip straight to the friend's part, it's no wonder he's so popular, dude is actually playing new game plus with relationships!
And because of all that, sans doesn't really have that much of a connection with them, it doesn't help that he doesn't have a lot in common with these people either, they lived their entire lives underneath a mountain, they have a different culture that he's not used to and doesn't know the ins and outs of, and they presumably all know every little thing about the mountain they call home, where as sans doesn't know and hasn't experienced any of this before, he's had to try and play it cool, pretending he knows what's up to not seem like an outsider, in order to "fit in"
Anyway, point is, while he may have a lot of "friends" those people don't know much about him, and thus, couldn't REALLY support him if it came down to it, but there is one person who would get it, just one, a very important one, papyrus.
If papyrus really IS from another world like sans, then he could confide in him fully, they are brothers, good ones at that, any trouble they may have had adjusting to this world, and worries, anything small or insignificant, they could talk about it, or not, and just chill knowing they are the same, and that, at the very least, they are not alone.
But when you kill papyrus, you take away a MASSIVE pillar from the structure that is his mental health, you take away not only his brother, but his most trusted confidant, the person who he values more than himself, his last remaining connection to his old world, his old friends, his old life, you're not just taking away his brother, your taking away a huge part of sans, one that he values very highly judging by the don't forget photo, and his genocide speech about letting go and giving up, which is implied to be referring to him trying to back home.
Anyway, these are angsty thoughts I had, maybe I'll find it cringe in hindsight and delete it, I just value sibling relationships a lot, being a brother myself, and wanted to talk about sans and papyrus's relationship.
