Underswap is an Undertale Role Swap AU and Fan Verse in which various pairs of characters switch roles with each other, with the subsequent story exploring how plot events alter, diverge, or stay the same because of this.
The original idea of Underswap was never a full personality swap, though Frisk/Chara, Flowey/Temmie and Burgerpants/Nice Cream Guy did fully swap personalities. Other characters either remained the same as in canon or were given a mix of traits to share between them. As the AU grew more popular, more full switches were made until almost everyone swaps with someone. Generally, characters will switch personalities as well as roles. Though some quirks tend to stick in places, or else are modified. Examples include; Sans taking on the role of the excitable, confident, extremely optimistic human hunter, while Papyrus becomes the laid back, protective bro following Chara (who is swapped with Frisk), and so on.
The creator of the Underswap, P0pcorn Pr1nce, has since left the fandom and deleted the original page. The AU lives on as a shared Fan Verse with various art, fanfics, music and fan games still being created.
Has a wiki here
and an entry on the Undertale fan wiki here.
This AU in general provides examples of:
- Adaptational Badass: Monster Kid, a canonically harmless NPC, inherits Asriel's role and everything that comes with it, including the role of final boss in the Neutral and True Pacifist routes.
- Cute and Psycho:
- Temmie. See Faux Affably Evil.
- Frisk, if the creator plays up their cuteness over the game's original kind of ugly sprite design.
- Demonic Possession:
- Frisk's ghost to Chara.
- Monster Kid possesses a Temmie doll in place of Asriel possessing a flower.
- Deranged Animation: P0pcorn Pr1nce's original version of the AU featured much more exaggerated and expressive character designs, in contrast to Undertale's Thin-Line Animation. Some other artists' takes go for a similar style.
- Dies Differently in Adaptation: Almost every character due to the nature of a Role Swap AU. They'll usually "inherit" the death of their canon counterpart. A few examples:
- Asgore being killed as the Boss/final encounter in the Ruins instead of New Home.
- In the Genocide route, Temmie/Monster Kid is killed by Chara (possessed by Frisk) instead of dying offscreen with everyone else when the world is destroyed.
- Sans dying in Snowdin as the Boss of the violent routes, and Papyrus dying in New Home as the Genocide route's Final Boss.
- Early-Installment Weirdness:
- As stated in the description, originally only certain pairs of characters swapped fully while others stayed the same or just switched a few quirks. Now almost every important character has someone to swap roles and personalities with.
- Bratty and Catty originally swapped with each other, but this was scrapped. They usually swap with Royal Guards 01 and 02 instead.
- Evil vs. Evil: Temmie vs Frisk if Frisk is portrayed as Always Chaotic Evil rather than a Well-Intentioned Extremist or Noble Demon. Temmie tends to be evil no matter what, at least until Monster Kid gets their soul back.
- Faux Affably Evil: Temmie, or rather, Monster Kid. They like to mess around by playing cute and dumb, but they're just waiting for the perfect time to drop the act and steal Chara's SOUL.
- Nightmare Face: Temmie filling in for Flowey.
- Personality Swap: Played with. If a full role swap isn't used, elements of this often happen instead.
- Spared by the Adaptation: A few characters get this:
- Undyne, like canon!Alphys, can only die at the end of the Genocide route when the world is destroyed. Otherwise she's The Unfought.
- Muffet and Royal Guards 01 and 02 gain shopkeeper immunity and can't be fought or killed. Though, like Undyne, they can still die at the end of the worst route.
