Plushies of temmies seem to exist in the universe of TS!Underswap since there is one in the kid bedroom in Asgore's house, and so it doesn't really seem too far of stretch to suggest that the Temmies are the result of a similar experiment which brought Flowey to life like in the original game.
The Seven Temmies are the previous Seven fallen humans
- The numbers match perfectly, and the Temmies being soulless can easily be explained by their human souls having already been collected. Being the only (former) humans in an Underground full of monsters, and likely bitter from getting killed to have their souls harvested, the seven have banded together to work towards a shared goal of getting the last human soul before the monsters do and taking back their old souls by force. Of course, going by their behavior, this wouldn't be a good thing; they're probably more interested in power than in feeling human emotion again...
- Since their old items are littered across the Underground, perhaps we'll have a corresponding Temmie show up to take up a more active villain role and antagonize Chara directly in each area, only to get foiled by Flowey, Papyrus, and/or any other new friends Chara's made.
The Temmie that tells the story when the game begins is Bob
In the original Undertale, there are
eight Temmies in the Temmie Village: One inside the shop, one barely hiding inside the wall, one trying to hatch a boiled egg, one allergic to itself, and three other Temmies who are similarly strange. Then there's Bob, the only one who has (at least) average intelligence, speaks proper English, and is possibly male (the other Temmies appear to be female). The Temmie who appears when TS Underswap starts up is dressed in old-fashioned gentlemen's clothing and calmly reads to you. Bob is the only Temmie who still has a soul and is different from the seven soulless Temmies we see in the game proper.
Monster Kid is the new Flowey
Monster Kid and Asriel have their roles reversed. This Flowey has spiked petals, just like Monster Kid has spikes on his head. And while he does introduce himself the same way as
Undertale Flowey, he otherwise doesn't have the same nastiness of the original. The only reason the devs didn't make him say "Yo!" was because that'll be
too obvious.
Frisk is the new Flowey
Since character relationships (Asgore and Toriel as an estranged couple, Papyrus and Sans as a goofy brother tag-team) generally carry over from the original game, it would make sense that Frisk would be friends and partners with Chara as Flowey: Chara was Frisk's narrator in the original game and seemed to be on their side no matter the route, it could be the swap has Frisk as Chara's helper and ally in this one, which is why Flowey also doesn't seem to really mind what route you choose. Flowey admitting he/they have been less-than-moral in the past like Chara during non-Pacifist endings could be a nod to Frisk's capacity for doing terrible things under the player's control, like Chara. Depending on how the determination experiments went in this AU, Frisk-as-Flowey could also make sense: while the others might've been brought back by determination experiments, perhaps Frisk brought themself back to life as Flowey through their own determination and that's why they can remember resets as well. Alternately...
Frisk is one of the Tems
Connected to the "the seven Temmies are the previous seven fallen humans" WMG above. Frisk is either:
- The first Temmie we meet: like Frisk, this Tem wears a striped shirt, suggesting they're a kid. All the fallen kids are a Vague Age, but Frisk is the only one other than Chara who we know for sure is a kid and we only see one Temmie in Undertale wearing a striped shirt (all the other Tems wear solid-color shirts, implying they're at least teenagers). Compared to anyone else other than Monster Kid, them having been Asgore's child and opting to leave when they realize he's coming would better parallel Flowey having been Toriel's son and getting blasted away by her. In the Genocide ending, this Temmie also mentions that they usually just do what the others tell them to, which could be a reference to Frisk being our player character in the original game;
Or,
- The Temmie "leader", who is the last of the Temmies to show up. In this AU, Frisk would be the first fallen human, which would make them the most experienced and knowledgeable about the Underground, so other humans might defer to them. The lead Temmie also seems to have the strongest rivalry with Flowey, as the two talk directly to each other with the rest of the Temmies silent (even in the Genocide ending, when another Temmie talks to Flowey, he ignores them and knocks them away) and the leader Temmie says Flowey's name with quotes, indicating they know his/their true name; if the Temmie is Frisk and Flowey is Monster Kid, it'd make sense that it'd be so personal between them, since they were best friends and adopted siblings in this AU, possibly with resentment from a failed Thanatos Gambit souring their relationship. The leader is also kept in shadow, so we wouldn't be able to see if they're wearing Frisk's iconic blue-and-purple shirt or not.
This Chara is the same one from Undertale
While all the major characters we've seen who've gotten new designs for
TS!Underswap, Chara is still wearing the same outfit as from
Undertale. They're also still in the habit of narrating, we see a
momentary red glint in their eye when they're first getting up, and they're still the character we name.
In Undertale's Genocide ending, Chara wanted to "move on to the next". Possibly, they were successfully resurrected in their old form by all the power they gained, and with us playing the game they were able to move onto the next world with us (hence the quick flash of red eyes like you see in Undertale's Soulless Pacifist ending). For those who didn't complete Genocide however, their Chara was still pulled along with them and reincarnated into this new world, since we have once again called their name by naming them in this world too, so the Chara of people who never played Genocide won't have to be stuck as a lonely specter forever (in which case the red eyes might be a sign of possession, in Soulless Pacifist by Chara taking over Frisk's body, and in TS!Underswap by the player assuming control over Chara).
Chara is an amnesiac to avoid the issue of what they'd remember player actions from Undertale — maybe jumping worlds cost them their memories along with any stat increases, resetting them without cheating with the files. Either way, it's their chance at a true second chance, alive again and free of memories of any Genocide runs their player might've done. (Unless their player chooses to pull a Genocide in this world too, at least.) Alternately...
This Flowey is the same one from Undertale
After all, he showed up to protect his old pal Chara from getting their SOUL ripped out, and is trying to buddy up to them — perhaps using this Chara as a
Replacement Goldfish for the one he lost in his world? Considering the Genocide ending version of Flowey ends up,
well, and the Pacifist ending version
genuinely turned over a new leaf and is no longer obsessed with having Chara back or with using people for his games, the likeliest candidate would be a post-Neutral Flowey.
Flowey still absorbs the six human SOULs in all Neutral endings even if you don't fight Photoshop Flowey, was capable of transporting Frisk and himself to "My World", and of communicating with Frisk in-person wherever they ended up (it doesn't seem to be the Underground, since enough time is implied to pass before the phone call that monsters would've seen them), so it could be that he is capable of traveling to other realities and checking in on other versions of his world and the people in them. While waiting for the human in his world to reset, he might have realized that Chara wasn't dead yet in this world, guessed that Chara would be showing up alive, with their original SOUL, as the next fallen human, and has been waiting for them, for the same reason he just watches and comments on whatever you do in normal runs of Undertale: for his own curiosity and entertainment, with a world and people so similar yet different from his own (and arguably a dash of sentimentality for his friend/sibling, since according to this WMG's logic he specifically picked a world where a Chara was alive and didn't already have a relationship with the world's Asriel, so Flowey could theoretically fill in). As for his rivalry with the Temmies, maybe he's realized they're his replacement in this world and is not amused. Despite still having the power of six human SOULs inside of him, Flowey is biding his time with the appearance of a simple golden flower, to see how things play out first before he starts throwing his power around.
Frisk isn't a Tem or Flowey
... they're an invisible force aiding Chara while the player controls them, and once again their personhood will be hidden from the player until the very end of a certain route. Being an unseen ghost and partner to our player character would match up Frisk's role with the one Chara had in
Undertale most closely, and by keeping them as
The Voiceless would avoid committing them to them having a specific personality the way making them a Temmie or Flowey would.
Confused and uncertain upon arriving in the Underground, Chara is seeking help and advice (unseen by us) from Frisk, whose ghost was awakened from their grave and attached to Chara by their determination, hence why Chara keeps asking an unknown third-party (the player, or Frisk) if they should do specific things. Chara is actually addressing Frisk, not us, but since they're still The Voiceless and we're the one putting in commands, we're once again treating Frisk as just our stand-in. To parallel Chara making their presence more known in Genocide in Undertale, Frisk may be the one changing Chara's dialogue prompts in Neutral and True Pacifist in TS!Underswap: not out of malice, but because they're insistent on pushing Chara to keep going and find a way to help the rest of the monsters in the Underground (despite how much it upsets Chara — since Chara was implied to be soulless after their death in Undertale, this Frisk may be soulless as well and have a Lack of Empathy despite still being well-intentioned). Their role will be made more clear in the True Pacifist ending, where Chara will finally address them by name to thank them for their guidance when Chara was confused and vulnerable.
Chara will fully believe that Sans is NOT Crossbones, despite (or because of) the
Paper-Thin DisguiseAnd if and when they learn otherwise, it'll come as a huge shock to them. Sans and Papyrus will either be smug that it worked, or amused and befuddled about how they fell for it.
Rule of Funny.
- To add to this, Crossbones' Secret Identity may be an Open Secret to literally everyone in Starlight Isles (and maybe the rest of the Underground) EXCEPT Chara and Koffin-K, again for pure Rule of Funny.
- Confirmed, but it seems that everyone doesn't seem to know Crossbones is Sans.
Papyrus owns fanon Underswap-Papyrus' outfit (orange hoody, brown shorts)
It's what he wears when he's cleaning his usual outfit on laundry day.
In the second demo, Asriel will say "Greetings" and may speak more eloquently overall.
Since Chara meets Asgore first and we see them copying his greeting of "Howdy!" when talking to the Mad Dummy. Meanwhile, with Asriel never having met Asgore per
Word of God, Asriel will have spent much more time with his mother and likely taken on more of her mannerisms in this world (and because he'll be older, he may also be trying to sound more mature and respectable as the crown prince to his people), switching up which parent
Chara and Asriel take after most.
- Jossed for the second demo; Asriel only appears once and isn't able to be spoken to yet.
Asriel will have a bigger role to play than Monster Kid does in Undertale
Since he's such a beloved and important character, and Chara's friendship with him is a defining part of their story. He'll get upgraded to the main cast and having a hangout session of his own, Chara will be able to call him to talk like how Frisk can call Papyrus and Undyne in
Undertale, and he might get his own subplots (maybe that Chara helps him deal with in the hangout?).
Gaster will show up, but the lack of any solid information about him will be his whole character, as a joke.
He'll be
The Faceless like Riverperson, and Sans and Papyrus won't mention him at all to indicate if they have
any connection to him or not — or lean in on all the common Gaster theories, talking about their father,
and their other brother,
and their ex-boss, etc all without naming any names to pinpoint which one Gaster is supposed to be. Heck, you might not even be able to talk to him — maybe he's only mentioned by one person, who only talks about him to say he's doing something in a room up ahead so you know he's there, but the way to it will be blocked, just to mess with players.
Deltarune characters will appear in the game.
Because why not? Asgore's dialogue in the Winter Clock extras makes an AU version of Rudy and his daughters canon to
Undertale. Susie, Noelle, their classmates, Rudy, etc may appear in one area or in different zones (perhaps the Hollidays will be the winter-themed Boreal Bluffs, while Susie — being a lizard/dragon monster — lives in Starlight Isles, or they're all in one area attending the same school). The question is, what age would the classmates be? Kids the same age as Chara, or teenagers the same age as their canon counterparts?
- Confirmed; Catti and Jockington make an appearance in Starlight Isles, and are shown to be younger than they are in Deltarune.
There are two first person narrators.
The idea that there's an unseen, invisible partner aiding Chara has been brought up above, but what if they
are narrating?
It's possible they are both speaking in-person, making impossible to tell which is which. There's still going to be a twist with the name we entered.
The fact that there's another entity as shown when railroading Chara into leaving Asgore and that it's clear that Chara is amnesiac and the name we entered is only their best guess at who they are leaves this troper suspicious.
The Dummy encountered in Crystal Springs will be a
Bait-and-Switch Boss where you'll still fight Mad Dummy
Since the swapped characters still have the same personalities, it's likely that the original Dummy will still be quiet and not want to fight. There might still be an encounter with it if it's blocking the way, but it won't attack and the options will be similar to the ones in
Undertale, where the only way to get past it is to make it "tire of your aimless shenannigans". However, just when the encounter is about to end, the Mad Dummy will show up, get mad at whichever options you chose, and then fight you until someone (most likely Mettacrit) shows up to intervene. The Mad Dummy will still be mad at you until they become Mad Mew Mew later on.
The final boss of Ruthless will be both Papyrus and Sans.
When you're about to kill Crossbones on the Ruthless route, he quickly swaps himself for a cardboard cutout. Everyone else still thinks he's dead, including Papyrus, but it's likely that he will eventually find out that Sans faked his death. If you continue with the Ruthless Route, Papyrus may eventually lose hope that you can change and finally decide to fight you, but Sans will also team up with him. Alternatively, the battle will have two phases: Papyrus on his own, and then both brothers after Sans appears and reveals himself to still be alive (if he hasn't already).
The True Pacifist Ending will have Chara's options change again, this time by themself
A recurring thing throughout the game is that sometimes, Chara's dialogue options will change before you select them, making them say something different from what they wanted to say. In the True Pacifist ending, they may have the option similar to
Undertale's ending where they can either stay with Asgore or not; however, choosing the second option may also change to Chara wanting to stay with Asgore, symbolising them finally taking control and breaking free of whatever is changing their words. It would also be a good call back to when they weren't able to tell Asgore they wanted to stay with him at the start of the game.
