headcanon dump

[seriff]

None of the stuff below is meant to imply that my interpretations are ~the canon readings~ or that we can't play together under totally different assumptions! This post is partly just so I have something to easily point to as a springboard for later on, and primarily for some harmless pretentious fun, ngl. But on the off chance you do want to use this post or another channel to nitpick a point / just talk fan theory, I'd be delighted c:

It does imply THE SPOILIEST SPOILS, including story elements originally found through datamining and only introduced into the unmodified game with the v1.001 patch. Proceed with caution!

(Things in purple are things with no basis in the game afaik, just things I happen to like.)

Birthday: March 31. Regardless of whether this is an actual birthday or something less mundane, monsters in the underground seem to use the same calendar as up on the surface and celebrate analogous cultural things.

Sans and Papyrus are just skeleton-shaped monsters, not undead. Whether it's possible for a human to become or take over a monster (say, in the way Chara temporarily took over Asriel after their death) is a question I'm going to conveniently sidestep here!

Sans is the older brother, possibly by quite a lot, although age might matter less to monsters in general anyway. Gerson and maybe Napstablook indicate it varies a lot more, at least.

The "YOU TWO" in the Log Entry 17 purportedly missing from the True Lab refers to Sans and Alphys. Alphys would then also be the other party Sans refers to when he mentions "our reports". They know each other through having worked together before, originally under the last Royal Scientist WD Gaster, and get along well to boot; Sans' expertise was/is more on the theoretical side of things, in contrast to Alphys who seems like more of an engineer in her method and outlook. Neither of them are good with lightbulbs.

Said work got pretty shady during the period where the DT Extractor blueprints would have hailed from, sufficiently shady for Sans to decide it was best to keep Papyrus entirely in the dark. It dealt not just with Determination but more generally manipulation of the SOUL, and included the use of each other as test subjects. EXP and LV as quantifiable concepts also originate from this line of work; they have something to do with the stability of the reality around them, hence why the worst route in the game ends the way it does.

It's possible that Alphys' work on Mettaton originally brought her to Gaster's attention when he was the Royal Scientist, rather than / as well as Asgore's - harnessing a different kind of SOUL through robotics seems like something he'd see as relevant.

Sans, on the other hand, was never the Royal Scientist in any reality. Assuming the naming theme holds up, he might have landed an assistant role through a prior relationship/acquaintance with Gaster instead. Asgore preferred to keep most of his thoughts about the barrier at arm's length and rarely checked in on his scientists, but he and Sans are still in occasional contact, if only indirectly by way of Alphys.

The other people in the original basement photo are "followers" of Gaster, more of Sans's previous coworkers, who were erased along with him.

In a failed experiment examining the effect of DT on spacetime, Gaster managed to wipe himself out of reality, as you do. He never existed in the timeline Sans remembers. The "back" Sans has given up on returning to is the previous universe where he did. Even so, the most Sans could do was piece together from leftover blueprints and machinery that such a universe was probably there at one point - he no longer directly remembers Gaster either. At best, he might for a time have retained some vague partial memories, like most characters do of resets in the present day; that would be where the drawing in his lab comes from.

One way or another, the few leftover clues from Gaster's erasure prompted Alphys and Sans to look further into the spacetime research they'd started. However, despite their best efforts, it was prohibitively difficult to turn the data they managed to gather into anything practical. It didn't help that Alphys had to juggle all the responsibilities of Royal Scientist in this reality and had never been quite as naturally brilliant as Gaster was.

Frustrated, then eventually depressed, Sans left the lab and the brothers' place in the city (though he either remained on Asgore's payroll or had savings), taking a still and forever clueless Papyrus with him. He continued to muck around a little with some promising-looking machinery in his own time, but neither he nor Alphys could ever get further than what's seen in the game. After all, that machine was built to interact with the fabric of a different reality.

The True Pacifist ending really is the best of all possible endings. Gaster's research wasn't pleasant, and would eventually have led somewhere even less fun.

Sans is slow to trust, and in general a lot more reserved than he looks. Out of the major supporting characters, he's arguably the most hesitant about warming up to the main character even when nothing dealbreaking happens. The main present-day significance of the prank involving his room is showing he finally has enough faith in Frisk to loosen up.

Before True Pacifist endgame, he hasn't met Flowey in the timeline he's aware of; he knows about the True Lab and probably the broad strokes of the experiment, but not exactly why it failed. Though he suspects that there's something more than an echo flower bugging Papyrus lately and can guess at there being some connection, he never gets a chance to follow up while still keeping tabs on the main character. This is largely because Flowey has had plenty of resets to practise avoiding him by now, after never quite managing to get past him.

His spacetime-manipulating powers are the result of screwed-up DT-related experimentation, whether before or after his stint as a fully-fledged researcher. The method could have been more refined or otherwise different than Alphys' desperation-driven "FUCK IT LET'S INJECT EVERYONE WITH EVERYTHING" approach, though. In any case, whatever he has still doesn't come close to the innate determination of a human, so it makes sense that he has no continuous memory or SAVE ability of his own.

His lasers, on the other hand, are more magitech in nature - he could feasibly show another monster (say, Papyrus) how to use them if the stakes were high enough for him to get worried. They may or may not still be related to DT on the side.

Remember that gag about "constantly emitting slime"? DT doesn't cause a monster's body to fall apart right away: in Undyne's case it took an entire lengthy all-out brawl, and with Alphys' patients it took a few days of normal walking and talking. If Sans has messed around with DT before, this could have played into how he became as depressed, inactive and apparently physically frail as he is... and why, unlike Papyrus, the only time he appears to sweat in-game is after a ways into his fight. Ew, though.

Less horribly, that research would be why he knows what behavioural tells to look out for and set up his various elaborate methods of fourth wall checking. If Alphys was involved in this research too, there's every possibility she knows a few of the tells as well, but it's still feasible if she doesn't - and to be fair, in every route where she meets the main character in person, she explicitly wants to raise as little suspicion about herself as possible.

In every timeline, he's in contact with Alphys throughout the game.

Like Alphys, Sans' knowledge of humans and the surface world is secondhand - more extensive than common knowledge by a long, long stretch, but researched rather than seen on the surface.

Unlike Alphys, he's naturally cagey and used to compartmentalising; even heavy secrets don't tend to grind away at him for a long while. But he does get a kick out of talking circles around people just like he enjoys pranking them, so Alphys is actually slightly better at keeping her mouth shut when not flustered. ...She's often flustered.

Related to talking circles around certain people: it's not the puns themselves that annoy Papyrus (he will cheerfully make his own when Sans isn't around or to one-up him), it's the sheer gall of someone sitting around and punning when they could be doing literally anything else. And Sans is happy to exploit this!

Normal bones have blood in them too! It's just that since a monster's physical form is exactly as tough as their SOUL, by the time they're that badly hurt, they're probably a goner without DT-related fuckery anyway. (So Papyrus' body doesn't hold together long enough to bleed.)

Papyrus is a young adult, not quite old enough to still have contacts from or any attachment to life before moving to Snowdin. If the majority of monsters age at a similar rate to humans, this might put the skeletons' arrival somewhere in the range of 10-20 years ago.

Gaster's tenure as Royal Scientist came after the six previous humans had already fallen down, so his disappearance, Sans' subsequent research and Flowey's shenanigans couldn't have been affected by any of their powers of SAVE/LOAD. The only anomaly Sans knows about in any iteration of canon is the main character.