Canon Underswap research
By Demirramon
Fanonswap made a total mess of Underswap, and with Morty trying to avoid anything related to Underswap, there’s no one to give proper answers to many unanswered questions.
This is intended to be a list of actual Underswap facts to separate it from fanonswap, with evidence from Morty itself and nobody else.
This will be really extensive and won’t omit details, even if they are small and seem pointless. If you just want to know which characters swap and how do the swaps affect them, go to the research's summary.
Let’s start with the first time Underswap was mentioned ever.
First Underswap post ever
OK SO, I thought what if there’s an AU in which the bros personalities are (somewhat) swapped??? let’s call it, uh, underswap? bc honestly one thing i love more than. passive chubby pun skeletons is HYPERACTIVE chubby pun skeletons that love to make tacos and share them with his brother
Here’s the first things we got from Underswap.
From the text on the post we know that:
- Sans’ and Papyrus’ personalities are somewhat swapped.
- Sans is hyperactive.
- Sans likes tacos just like Papyrus liked spaghetti.
- Sans still makes puns.
Also, design-wise, we can observe that Underswap Sans:
- His eyes are now blue, with dark circles in them.
- Has eyebrows.
- Wears a blue cape, larger than Papyrus’.
- Wears armor-like gray clothes with a few light blue details and a white shirt underneath.
- Wears dark-blue pants.
- Wears blue boots of the same color of the cape.
- Apparently, he can open his mouth.
With this post alone, we can see how bad the fanon version of Underswap sans ended up.
Those are the main points that the fandom got completely wrong:
- Sans wears the same kind of blue (or a really similar one) that he wears in the original Undertale design, not light blue.
- He still has the blue soul and blue bones powers, not an “orange attack”.
- His age doesn’t seem to change at all. He’s not a child.
- His personality is not completely swapped with Papyrus. He still likes puns, for example, he doesn’t hate them (neither does Papyrus in canon Undertale, anyways).
- His eyes are not stars.
- The name “Blueberry” is not mentioned at all.
Now, we can move to the next post.
Second post about Underswap
more of the underswap au that no one asked for but still
what if swap!papyrus wears those indirect text post shirts by zazzle-poetry
he almost always slouches over to sans doesnt feel small
In this post we get to know more about Underswap Papyrus:
- When you first meet him, he would use a mask with glasses and a nose.
- He slouches over Sans to not look too tall compared to him.
And also, about his design:
- He might wear hoodies with “indirect text posts” on it, similar to those from Zazzle.
- He smokes.
Also, there’s new stuff about Sans:
- The shape of his eyes can change to show different emotions.
- His laugh, replacing Papyrus’ “Nyeh heh heh”, is “Mweh heh heh”.
- He seems to call puzzles “traps”.
And we debunk some stuff the fandom assumes wrongly:
- He’s not smoking weed. This is stupid, why do people assume that anyways?
Mettaton and Napstablook
[[ Give me Underswap!Napstablook and Mettaton in which Blook is the best DJ/Radio Host in the underground and Mettaton is a shy ghosty who sits in his house and writes romance stories. ]]
By reblogging this post, Morty agrees that:
- Napstablook and Mettaton will be swapped.
- Napstablook will be a DJ and/or a Radio Host, instead of owning a TV show.
- Mettaton will be a shy ghost who writes romance stories in his house.
More details about swaps
hello yes i would like to write some underswap fanfic, can you give us anymore headcanons? like who else has swapped and whatnot? and does sans still like puns or is that Papyrus' thing? does pap still make spaghetti?
wow that’s really cool!! i kind of wanted to swap their main traits but not everything literally, ex. papyrus is more into practical jokes than puns and sans likes riddles instead of puzzles. i also thought it would be fun if sans was into mexican food instead of pastas ex. he enjoys making taco’s/burrito’s.
as for the swaps here’s the ones i had in mind/that have been suggested for now:
pap swapped with sans (obviously lmao)
undyne (shes now the royal scientist who enjoys cartoons, she no longer had the eyepatch)
swapped with
alphys (the fierce head of the royal guard that wields a huge battle axe and has dino skull themed armor, instead of the eyepatch she has a claw scars vertically across her left eye)
toriel (the ‘ruthless’ leader of the underground screwed up and killed the humans)
swapped with
asgore (escaped former king tend to fallen humans makes them cakes, was disgusted by toriels actions and left her)
mettaton (shy ghost that hides in his house dreaming of becoming a famous star one day/ tends to his diaries ussually)
swapped with
napstablook (number 1 radio DJ in the underground, his body designed by undyne has retractible turntables to mix some sweet jams)
i don't know about the other minor characters but this is it for now!! this rant has been long enough… *cough*
- The swaps won’t completely switch the personality, some stuff will change.
- Papyrus is more into pranks than puns.
- Sans likes riddles more than puzzles.
- Sans is not just into tacos, but also likes to prepare mexican food like burritos.
- Undyne and Alphys are swapped. She doesn’t have an eyepatch anymore.
- Alphys wields a huge battle axe, and her armor is dino skull themed. She has scars vertically across her left eye instead of an eyepatch.
- Toriel and Asgore are swapped. She’s the one who killed the humans.
- It says that Asgore bakes cakes instead of pies, but that gets discarded later.
- Mettaton is a shy ghost who dreams of becoming a famous star someday and writes a lot of diaries about his fantasies.
- Napstablook is a radio DJ. His body has retractable turntables to mix music.
First drawing of Underswap Alphys
The design talked about in the previous post is revealed.
- Alphys is bigger and stronger, and her weapon is a huge axe. Her armor is gray and a dark shade of green
Note: there’s a problem with this drawing. The scarred eye was supposed to be the left one, as stated in a previous post and corrected in a future one.
Knowledge about resets
wait so who has knowledge of the resets? is it papyrus? or sans? that would be interesting if it was sans- like this sans never gave up no matter the resets, but it being papyrus would make more sense
that would be papyrus in this case
- Papyrus is the one who has knowledge about resets in this universe.
- Sans, unlike in Undertale, doesn’t know about this.
Last genocide run boss
so in underswap instead of fighting sans during the genocide run, we fight papyrus instead?
Yup!
- Papyrus will be the final boss of the genocide run.
What does Papyrus sell?
if sans sells hotdogs, in underswap au what does papyrus sell? corndogs?
Yes.
- Papyrus will sell corndogs instead of hotdogs.
Frisk and Chara
So in underswap, would Frisk and Chara be switched too? As in Chara is the pacifist and Frisk is the homicidal 9 year old
I think that would be the most logical yes, but they both don’t really have a lot of personality so it wouldn’t really change a lot though.
Also talked about it in this post
- Frisk and Chara are swapped. Chara is the player.
Reveal of the whole cast of Underswap*
*He later talked about more swaps, though.
I present UNDERSWAP (almost) the whole gang, it’s finally done.
More details under the cut. [full res]
All the swaps;
Sans - Papyrus
Undyne - Alphys
Toriel - Asgore
Mettaton - Napstablook
Grillby - Muffet
Burgerpants - Nice cream rabbit
Temmie - Flowey
(Muffet has a cute maid cafe called muffet’s and she serves orders on her roller skates)
Thanks to @coastrobbo and everyone who left suggestions in my inbox! X
We can see a lot of stuff here, let’s make a list:
- We can see how Papyrus’ hoodie is orange.
- Undyne and Alphys are swapped.
- Undyne seems shy and nerdy, and wears a lab coat. She’s not slouched like Undertale Alphys, though. She wears glasses and has both eyes.
- Toriel and Asgore are swapped.
- We can see that Asgore wears a robe similar to Original Toriel’s, and has a pie on his hand. It’s implied that he might have Toriel’s cooking skills., though.
- Toriel wears an armor similar to Original Asgore’s. Instead of a trident, though, she has a sceptre as her weapon.
- Mettaton and Napstablook swap is confirmed.
- Mettaton is a ghost now. He has a fringe similar to his Mettaton EX form.
- Napstablook is in Mettaton’s robot body. They have a cap over him and, as stated in a previous post, has retractable turntables that make them look like a DJ robot, which he is.
- Grillby and Muffet are swapped.
- Muffet has a maid cafe where she serves orders on roller skates.
- She also wears a suit similar to the one Grillby wore.
- Grillby wears a colorful suit reminiscent of the 90s clothes and glasses with a spiral pattern on them.
- Burgerpants and the Nice Cream rabbit are swapped.
- They seem to have switched the place where they work, also inverting their personalities.
- Nice Cream rabbit smokes instead of Burgerpants.
- Temmie and Flowey are also swapped
- Temmie is the antagonist of Underswap, while Flowey got Temmie’s original personality.
So far, we can debunk this:
- Mettaton’s ghost is not pink, unlike a large part of the fandom depicts him. The whole picture has a pink-ish color.
- Napstablook’s robot form doesn’t seem to have a blue color scheme on their screen.
- Asgore, like canon Toriel, bakes cakes instead of making Tea like canon Asgore (That gets discussed a little later, though)
Flowey and Temmie
* (You feel…something.)
so @inklite and I were discussing character swaps… I don’t even want to think about what Omega Temmie looks like.
Link to the original post (reblog)
Nothing is confirmed here, but it’s seen for the first time how there might be a village full of floweys.
Possible Grillby’s fight mechanic?
Imagine one of Underswap Grillby's attacks involving his friend Heats Flamesman charging after you
pfff, yes perfect
Not sure if it was a joke or a serious answer, but, here it is.
Sans and Papyrus’ way to speak
So will Underswap!Sans still talk in Comic Sans but in all caps? And likewise for Underswap!Papyrus talking in lowercase?
yes! exactly!
- While keeping their original fonts (obviously), Sans will talk in caps and papyrus always in lowercase.
STMPWYFS or Megalovania?
Wait... so would that alt. version of "Megalovania" play when you fought Sans, or would "Song That Might Play When You Fight Sans" play?
Song that might play when you fight was my original choice for him, because it’s so cute and upbeat. But that mix of megalovania was pretty sweet too
- Since the beginning, Morty intended to use a STMPWYFS variation for Underswap Sans’ fight.
- Even if he says he liked a megalovania mix they sent to him, that doesn’t make it his theme.
- Passive megalovania can fuck off.
Rhythm-based attacks for Napstablook?
ok but hear me out: rhythm game based boss fight for Napstablook. You have to follow/copy the beats he does or you take damage. He'll even let you freestyle (read: give you a chance to deal damage to him because he's cocky and over confident).
OH FUCK YEAH GOOD SHIT
- Napstablook’s boss battle might have a rhythm based attacks.
Sadly, there’s no more information past this point.
Morty (Popcornpr1nce) stopped posting Underswap stuff on his main blog, and made a new one: underswapped.tumblr.com (not underswap.tumblr.com because someone decided to make a “another kind of underswap” and stole the url).
Sadly, because of how badly the fandom behave, the creation of the abomination we know as “Blueberry”, the tons of fontcest that happened, etc. made him not want to know anything about Underswap and deleted the blog, so this is all we have.
... However, there seems to be an archived version of the blog right here.
Sans’ clothes during the date
the most important question: would sans wear a "cool dude" shirt on the date with him or no (and is there anything else that is different about this. im asking for a friend)
he would absolutely do that
- mod popcorn
- Sans will still wear a “cool dude” shirt on his date.
Catty and Bratty?
I'm going to guess the only difference with Bratty and Catty is that now they wear the other one's outfit.
i mean, yeah
- mod popcorn
It looked like Catty and Bratty were going to swap their clothes at first, but that stopped making sense since this newer post:
ok but lik e wHAT IF BRATTY AND CATTY WERE SWAPPED WITH THOSE TWO GAY ROYAL GUARDS
thats a really good idea!!!
-mod popcorn
Has anyone came up with the Underswap headcanon of Royal Guard 1 and 2/Catty and Bratty swap? I could totally see it.
yes i believe theres been an ask about that! i really like that idea
-mod popcorn
- Catty and Bratty are swapped with RG01 and RG02
Alphys genocide name
So... Underswap Undyne the Undying would be... Alpha Alphys?
You know that’s not half bad.
I’ll run it through with my better half and see what they think.
-mod Robbo
- Alpha Alphys seems to be the name of “Alphys the undying” for Underswap’s genocide run.
Papyrus and Asgore
instead of sans and toriel bonding over puns do papyrus and asgore bond over puzzles
naaaaaaaaaaw
In this universe, puzzles are Sans thing, not Paps. But, I do think that Paps and Gorey would bond over a larger variety of jokes rather than just puns.
-mod Robbo
- Instead of puns, as they’re still something of Sans, Asgore and Papyrus would tell each other a wide variety of jokes.
Grillby
Muffet is swapped with Grillby right? Does that mean Grillby raises money for the flames in Hotland and a Spider won't forget you remembered?
👍👍👍
Made by flames, for flames, of flames, with flames!
-mod Robbo
- Grillby will try to raise money for the flames and sell fire-based food.
Napsta’s arms
If Mettaton loves his legs in the original canon, would Napstablook in this au love his ARMS instead? (Mettaton: Time to bring out the big guns! Underswap!Blooky: *loving pats his own arm* Got it~)
you got it right, my dude!
What’s a musician without their arms?
-mod Robbo
So NSB loses his legs in th fight?? " who even needs legs anyway, w arms like these //does a kickflip position with one arm
p much, my friend
-mod Robbo
- Napsta will like their arms just like Mettaton liked his legs.
Asriel and Monster Kid
Who is swapped with Monster Kid? ;<;
weve had a few asks suggesting asriel/monsterkid so i think that might be really interesting…
-mod popcorn
- Asriel and Monster Kid are swapped. There’s no explanation of how yet, though.
Sans’ Ketchup’s equivalent
Wait, so does Papyrus likes to drink mustard like how Sans drinks ketchup??
probably mayonaise, mustard is an evil condiment, more of an underfell thing
-mod popcorn
I just realised, if Muffet's the one that lives in Snowdin and has a business there (I can just imagine her tiny spider waiters) and that's where you're taken instead of Grillby's....would that mean that Papyrus would be drinking chocolate sauce or confectionry glaze or maple syrup or something like that? Somehow I find it hilarious that despite the image he projects, Underswap Papayrus has a sweet tooth
at first i swapped the condiment to mayonaisse but on second thought honey would suit him better considering muffets is a cafe and not a bar, so honey it is!
- mod popcorn
- At first, Papyrus was going to drink mayonnaise instead of Ketchup, but they think honey would fit Muffet’s better.
Sans’ and Papyrus’ stats
Out of curiousity are Sans and Papyrus stats still the same in this AU or are they switched as well? Since it would make a lot of sense for Sans to be denied into the Royal Guard if he still had only 1 HP and 1 ATK. After all if anyone were to lay a hit on him he’d turn to dust instantly.
i think it would be more hilarious if their stats just stayed the same
-mod popcorn
So role swap you say? So that means that Papyrus is still much cleaner than Sans huh. And Sans is still much more powerful, in a poisonous hp way. But that also means that Papyrus uses his attacks smarter and harder, even more creatively.
more or less!
-mod popcorn
- Sans and Papyrus will keep their original stats.
- Sans is not accepted into the Royal Guard because of his really low stats.
- Sans still has KR, while Papyrus uses smarter and stronger attacks
Original idea of the AU
I love this AU! but, hear me out, sometimes I headcannon it as more of a simple roleswap rather than personality swap (mad scientist undyne, silent but deadly Alphys who thinks people don't like her for being too scary, papyrus being wise but also much more forgiving than sans, etc) Idk! I wanna do some art of this au soon tho, it is Top Notch
that was also my original intend yes! :) i didnt want to swap the personalities completely because that would take all the fun out of it, instead they still keep glimmers of their ‘old’ personality
-mod popcorn
Do the characters retain some aspects of their respective UT counterparts' personalities (like Papyrus enjoying brain-training activities or Asgore being forgiving af)?
correctomundo, my friend. This isn’t a perfect personality swap, they all have some variation. Toriel is seen as stern motherly figure to all monsters. Asgore is more loved by the monsters in the ruins (cuz he’s extra sweet). Mettablook is keep all their glamour, but his very very shy, so it’s more pastel. Also some probably don’t make much sense undertale wise but came into fruitation because we love it, ie fuck boy Napstaton (he has all of Mettaton’s intense popstar power and over dramatism). But even then, Napstaton does have his blook moments, instead of a company required break he just “ain’t feelin’ it right now” and just takes a moment to rest before getting back into the groove.
-mod Robbo
- The original idea of Underswap was never a full personality swap. In fact, the core idea is more similar to Team Switched’s Underswap than what we know as Fanonswap.
Overpriced Muffet’s
what about an underswapped grillby and muffet? Grillbz would prolly have lots of food stands scattered around, but instead of being overpriced, his wares are WAY TOO HOT, and Muffet would be the chill cafe lady but has these horrible spider stuff for menu
Anon, please
the Muffet/grillby swap is already established, you can even see it in the line up pic.
Also, we think they’d pretty much occupy each other’s rolls without too much variation. Like naw, Grillbz will only have the two Fire backsales, and it second one is horrendously over priced.
But the fire food being burning hot and Muffet’s spider pastries are things I’ve been thinking about for a while.
-mod Robbo
- Muffet’s will be overpriced instead of Grillby’s selling points.
WOWIE!!!
Think Sans would say something like "WOWZERS!" instead of "WOWIE!"?
Quite possibly!
-mod Robbo
(edit: yes very good -mod popcorn)
- Looks like, instead of “WOWIE!”, Sans would say “WOWZERS!”.
Toriel
how much does toriel change in this au?
sheee basically takes over asgores role, but shes more guilt ridden about it. and instead of being nice shes more ruthless and emotionless when facing you in the final battle.
-mod popcorn
- Toriel won’t be as nice as Asgore. She’ll be more ruthless and emotionless instead of showing how bad she feels about it.
The magnificent Sans
does sans refer to himself as 'sans the great' like how papyrus does it in canon or is it something else like the 'sensational sans' or something like that?
i like the ‘supreme sans’ or the ‘magnificent sans’ but almost anything will do
-mod popcorn
- Sans, instead of calling himself “great” like Papyrus did, would use names like “The Supreme” or “Magnificent”.
Metta’s designs and Asgore’s food
I have several questions. Does Grillby hold a sausage sizzle in place of a bake sale? Is Mettaton shy about his fashion designs instead of music? Does Asgore cook quiches instead of pies?
yes, mettas probably shy about his writing and or acting. and yes
-mod popcorn
- Metta is shy about his designs (and probably stories as well).
- Even though he agrees about the quiches, it’s discarded later.
Possible scene of cooking with Alphys?
I just keep thinking of Frisk trying to cook hotdogs with Alphys, and in the pot/pan there's the water sausage plant, but it's the whole plant, stems, roots, and all. And Alphys is just cheering before saying that they're making ketchup from scratch.
cute!
-mod popcorn
Onionsan
I gotta ask, who does Onionsan swap with in this AU?
the duck in waterfall
-mod popcorn
- Onionsan and the bird that carries you over a disproportionately large gap swap.
Flames trapped in the ruins
the flames trapped in the ruins can escape, but they don't want to damage the snowy ecosystem don't even get the poor embers started on waterfall
*grillby says they’ll get hurt if they try to escape the ruins into the snow! with enough funds he can get them a heated limo…
-mod popcorn
- The flames are trapped in the ruins because the weather of Snowin would still hurt them because it’s too cold, even if they are flames.
- They might, also, be scared of destroying the ecosystem, but mainly they would get hurt.
(space reserved in case Mad Dummy and Gaster swap is a thing)
Asgore’s and Toriel’s food offers.
what if instead of making pie, Ruins Asgore made you a cup of tea instead, and Queen Toriel offered you a slice of pie when you got to New Home, before realizing you were a human?
thats a really good idea!
-mod popcorn
- Asgore would offer tea to the fallen humans, and Toriel would offer a slice of pie before noticing you are a human.
Mew Mew Kissy Cutie 2
underswap undyne thinks mew mew kissy cutie 2 is better than the original
don’t let canon alphys hear it…
-mod popcorn
- Undyne thinks Mew Mew Kissy Cutie 2 is better than the original.
Aaron and Shyren
what if shyren and aaron were swapped lmao
they are ;)
-mod popcorn
- Aaron and Shyren seem to be swapped, but they don’t explain how.
Anime is real?
Does Undyne still have her anime complex? Like, is she aware it's not real, or does thinking the mad world of human magic princesses and sword-robots help her drive to get out of the Underground?
shes aware that its not real but a girl can dream right?
-mod popcorn
- Undyne knows that anime is not real, like UT!Alphys.
- US!Alphys probably doesn’t know and thinks it’s real.
Papyrus bleeds?
so... does pap "bleed" in this au like sans does in canon, or did that not change??
yeah he does
-mod popcorn
- Papyrus would also bleed when hit in the last fight. However, it shouldn’t be red, as he doesn’t drink ketchup.
Friendliness pellets and Temmie Flakes
friendliness pellets shaped w/ temmie flakes
yes
- mod popcorn
- Friendliness pellets and Temmie Flakes are swapped.
Jerry
Does Jerry get swapped?
jerry gets ignored
- mod popcorn
Undyne’s accident + Temmie
Soooo... Undyne decided using the Queens dead child's favourite doll was a good idea for a vessel for the DT that wasn't human nor monster?
probably stuffed animals in general, maybe the doll ended up there by accident
-mod popcorn
- Undyne was experimenting with stuffed animals, including Temmie by accident, which brought them back to life.
Monster Kid’s adoption
Is Monster Kid the child of Toriel and Asgore?
have ya’ll heard of adoption?
-mod robbo
- Monster Kid is adopted.
Alphys’ axes
If Alphys replaces Undyne's spear with an axe, what would the bullet/arrow things become?
same but with rotating axes
-mod popcorn
- In Alphys’ fight, instead of arrows-bullets we will have rotating axes (same with the chase, probably.
River Person and Gaster
who would swap with riverperson
listen a lot of these characters are just enigmas with no real character traits and underswap wasn’t originally gonna add all of em.
we just don’t know
-mod Robbo
They said that there, but they changed their mind later.
For the person who asked about swapping riverperson, I personally swap them with Gaster. Just me?
gaster IS swapped with riverperson in this au
-mod popcorn
- River Person and Gaster are swapped.
What kind of anime does Undyne like?
So what kind of Anime does Undyne like? Shonen anime? I mean, Canon Alphys has Magical Girl Shoujo Anime as her favorite and I feel that Underswap!Undyne would like something different.
don’t tell Pops I said this but Undyne is a REAL manime and giant robot anime (and revolutionary girl Utena) fan ;p
-mod Robbo
- Undyne is a fan of manime and giant robot animes.
Dummy and Mad Dummy
I think Mad Dummy would be better switched with their dummy cousin from the Ruins. Imagine: your first battle (not counting Temmie), meant to teach you to talk your problems out, but instead the dummy gets irritated and starts attacking you. Then you come across another one, and you're afraid this one will attack you too. But turns out this one just gets bored with you and leaves.
that’s what I was thinking!
-mod Robbo
Looks like the Ruins’ Dummy and Mad Dummy are swapped, as opposed to what they said here and here.
- Mad Dummy and Ruins’ Dummy are swapped.
- You fight Mad Dummy in the tutorial.
Does Papyrus smoke weed? (oh for fucks sake)
I can't tell, and it confuses me more since I see people draw all three, but is Paps smoking a cigarette, cigar, or a joint/blunt/whatever?
cigarette
-mod popcorn
- Papyrus does not smoke weed.
Sans’ action figures?
So you know how papyrus collects action figures in undertale? What if underswap!Sans collects you spaceships
he’d probably collect scifi figurines (and spaceships yeah) and other snipets
-mod popcorn
- Sans collects sci-fi figures, spaceships, etc. instead of action figures.
Unfortunately, the archived asks end here.
I tried to research a little more into the blog, but I didn’t find anything of interest as the main purpose of the blog was to reblog Underswap fanart.
I’ve also made a summary document with the facts organized by characters, you can read it here.