The Multiverse is Terrifying: The Sans Suffering Rule
Sans doesn't have that problem, and that's a very bad thing.
The Undertale fandom has many, many works and concepts that alter the premise of the game itself. These are, loosely speaking, “AUs”, and they are so numerous in the fandom they’re practically synonymous with “Undertale fan work”. Sans is very popular across every part of the fandom, to the point many of AUs feature or even focus on Sans. He also has countless variations, outnumbering that of other characters. Indeed, it seems he’s the only character that exists in some “AUs”, and all the works the author can recall, only one doesn’t feature Sans, or an imitation or variant thereof.
Within the scope of Sans-centric work, it’s popular to have canon Sans (“Classic”) interacting with versions of himself from other timelines or universes, such as through Sans having a special machine or power that lets him travel to timelines or other universes.
If Sans were to become very familiar with the number, breadth, and details of AU Sanses and their worlds, he would conclude he’s very special and important, in a cosmic sense. And if that happened....the implications would be very, very bad.
Section 2: His suffering is disproportionate to his own lifespan.
Firstly, it is very common to make him suffer, and his suffering (averaged across popular fanworks/AUs) is disproportionate to his own lifespan, assuming he’s much younger the Asgore, Toriel, and Gerson. The ancient war veterans have lived for so long that there are many more opportunities to change the timeline within their own lives, necessarily splitting off into unique or severe suffering scenarios. Importantly, Toriel can die in many timelines, and Asgore dies in every timeline but one. (Gerson, strangely, cannot die in any canon timeline.)
Still, although people could show Asgore discovering the human killed Toriel or vice versa, and Gerson finding out the human killed Toriel or Undyne, the former is rare and the latter is unheard of. Indeed, as Asgore seems oblivious to the human’s murder spree in canon, he doesn’t face much suffering until the point he is killed in one hit.
Section 3: Sans often suffers in especially severe ways by his works’ standards.
Not only is he very popular, but it is very common to make him suffer, and frequently in ways that are unique or especially severe by the standards of the work.
Famously, his brother is often killed by a human. Although the overall number of murders in a Genocide Route is at least 101, and the human probably kills a bunch of people with close connections to later victims, the fanworks themselves don’t linger on this. Though fanworks could kill off the love interests of the RG01/RG02 and the Dogi pair, do so in horrific, prolonged ways, and make the survivor suffer, they rarely do.
In an Underfell variant (Papyrus vs. The Forces of LOVE), he’s abused by his own brother, he’s starving (PredatorTale/HorrorTale), is starving and also gets his eye ripped out and has a grotesque head injury (HorrorTale), he gets stuck in a state between life and death (AfterTale), he becomes an amalgamate with Papyrus (Sixbones)....
And he gets killed, over and over, even within ambiguous-canonical or more-or-less post-canonical works. (Canon Genocide timeline, Genocide timeline-based variants including AfterTale, and GlitchTale) Adding onto the special severity of suffering, Sans ends up having to kill a murderous or mass-murderous human in so many variants and repetitions.
Section 4. Sans Often Suffers in Unique Ways
Adding onto this, fanworks pile on extra-canonical (exaggerated mental health problems, Gaster Blaster transformation suffering) or ambiguous-canonical (e.g., Flowey Runs) types of suffering to Sans much more than anyone. After all, how many works show Flowey-Sans showdowns? How many works show him and only him (or W.D. Gaster and/or Papyrus with him) getting worn away by the resets and Flowey fights?
Additionally, across several works, he uniquely witnesses Papyrus dying first-hand (something ambiguous in canon), and picks up his scarf from the snow and cries. Only Monster Kid parallels this when witnessing Undyne get hit with a lethal blow, but they don’t actually see her turn to dust, and Monster Kid always survives afterwards. Through these things, Sans is further supported as cosmically special in his suffering.
Section 5. The Timeline Will Always Make a Sans (Eventually)
For Sans to exist, a timeline would need to allow for the decisions or phenomena that led to the point Sans could exist. Therefore, it seems that every universe will eventually conspire to create Sans, often using different methods to do so. It doesn’t matter whether he was made by resurrecting a human corpse, or by W.D. Gaster being his standard-issue father with a wife, or the same man creating him in a lab, or the same man (now a god) creating him from a black hole...he will practically always exist, in timelines that overlap with his probable creation time or not.
To be clear, a handful of works are exceptions to the trend. For example, InvertedFate actually has Sans doing slightly better than Canon Sans, nothing bad happens in LittleTale, and Sans doesn’t exist in Caretaker of the Ruins (probably because he wasn’t born yet).
Section 6: Implications
Were Sans to ever figure out the sheer breadth, commonness, severity, and uniqueness of his suffering across canon-associated and non-canon-associated timelines and universes, it would cause a lot of shock and existential terror. Any work where he doesn’t suffer a lot is an anomaly in an overall trend, or he doesn’t suffer there because he doesn’t exist there yet.
Importantly, though Flowey torments him in Flowey Runs, in some works Flowey (or his parallels) do not exist, don’t interact with Sans, or aren’t tormentors (Underfell). Therefore, since Flowey isn’t to blame in every variation, it would seem he is a favored plaything or a cruel god or gods.
Worse still, if Sans does not conclude he and all variations thereof are the playthings of deities...it is simply a natural rule of the universe, like water carving through rock, that Sans will eventually be created and suffer immensely and disproportionately. He cannot fight that, cannot argue against it, cannot befriend it.
It would have better for him to never visit other AUs at all.
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Reference
For reference, these are the AUs/fanworks the author considered, consciously or unconsciously, for this analysis. Some may be missing. Note that some don’t feature Sans, don’t feature canon-unusual levels of suffering, or don’t feature Sans yet.
Caretaker of the Ruins, LittleTale, PredatorTale, HorrorTale, Swap Out (Underswap), Kaitogirl’s Underfell (Underfell), Soulfell (Underfell), Papyrus vs. The Forces of LOVE (one chapter, fanfiction, Underfell), Handplates and Sixbones, Underlie, The Choice, Pulling a Tooth, Storyshift, InvertedFate, GlitchTale, TimeTale, ScrambleSaga, Entity Neo, Soul Dichromatism, We Need to Talk (Gasterblaster AU, though not for Sans specifically and not that focused on Sans), Spectrum (Gasterblaster AU), Trust/The Best Revenge (Gasterblaster AU), Fallen Flowers, The Anomaly (Post-Canon), They Say He Shattered (Post-Canon, Mixed Timelines), Time-Scar, Over the Void, Cost of Living, Heart and Soul, Chocoblook, Zombietale, Charatale, Mysterytale (Crossover), Unexpected Guests, Appreciate Your Bro Sans (actually happy Sans), Hard Mode, Ghost Switch, Growth Spurt AU, Deeperdown. Name the Fallen (Papyrus shouldn’t exist here; everything thinks he’s a human), Flowey is Not a Good Life Coach.
Do you draw comics if you do, could you draw a comic about what the three papyrus (UF,UT,US) would do if someone asked about if UF and UT sans have the same changing eye shape as US Sans
