NOTE: This AU actually does exist. I was just too afraid to post it on the actual Undertale AU Wiki, since it's a bit jokey, and I'm a paranoid person.
UnderSwitch is just another switch-up AU. It sort of combines Storyshift with Underswap, not quite fully swapping personalities fully.
The following switches occur:
The Protagonist remains Frisk.
The Soulless One is Flowey, but a different Flowey, with a different design. I'm just too lazy to change his name.
The Caretaker is Alphys.
The Judge is Lesser Dog, also known as Lez.
The Ambitious is Greater Dog, or Bewoulf to call him by the name he goes by in-AU.
The Captain Of The Guard is Asriel.
The Recluse is Muffet.
The Royal Scientist is Sans.
The Celebrity is Papyrus.
The Monarch role is taken by two characters, Dogamy and Dogaressa. Unlike in Undertale, the royal couple did not break up, and as such the role is taken by two characters. Alphys retreated to the Ruins after being exiled for creating the first two Amalgamates (Endogeny and Reaper Bird). Sans created the rest by accident.
The Soulless Angel is Doggo.
The Fallen remains Chara.
Minor Roles/Fun Value Roles
Fun Value/Erased Roles
The Forgotten Scientist remains Gaster. His followers continue their roles, unaware their surroundings have changed.
The Inactive remains Dummy.
The Accidental God role is taken by a large amount of cats, who rotate periodically. The Irritating Cat and the Interrupting Cat look like opposites, but share similar personality traits.
The Trusting Role remains the Snowman, but he has been changed into a Snowperson to retain some sense of actual switching.
The Secret Boss is Riolu; the three secret bosses (Riolu, who is a fake, So Sorry, and Glyde) have been rotated.
The Idoliser is Undyne.
The Restaurant Owner is Fuku, the flame girl widely believed to be Grillby's daughter.
The Nonexistant role goes to So Sorry; he exists about as much as Riolu did, and "appears" in the same place.
Mad Dummy remains in the Enraged role.
The Isolated remains Onionsan, who is as oblvious as the Gaster Followers.
The Cherished has been replaced by a cat; the cat doesn't seem to care.
The Transport role has been taken by Gerson.
The Chaotic Villager is a mix of Brattys and Cattys.
The Competent Villager is a single Catty named Bill.
Ragel remains the Enigmatic Dancer; he cannot move, so he cannot be switched.
The Club Member is Glyde.
The Amalgamates are not switched and remain in the Abominations role.
The Repetitive Vender is the Riverperson. He appears with nice cream, like the Nice Cream Guy, but doesn't seem nearly as cheerful.
The Bravery Vender is the Nice Cream Guy; we're basically just rotating the venders.
The Perseverance Vender is still Gerson; he runs the shop in his spare time, as he also has the transport role.
The Trash Venders role goes to Bob and Tem, the famous Temmies.
The Oppressed Vender is Mettaton.
The Outrageous Vender is Napstablook.
The Village Shop is run by Bratty and Catty no. Whatever.
The Blind role goes to Monster Kid. He has arms now, but at the cost of his sight.
The Pettable is.........a Temmie. Most of the dogs are Temmies.
The Unit Pair is Toriel and Asgore.
The Playful role is another dang Temmie.
The Other Pair role remains the same. I didn't have the heart to break em up.
There really is no plot. It's just random switching. However, there is a little backstory.
A Little Backstory
The first part is anticipated. Chara falls, Doggo finds them, both die eventually, blah blah blah.
Alphys is the Caretaker because she was driven into the Ruins after being exiled. She was exiled for creating the first two Amalgamates, Endogeny and Reaper Bird. She laments on the fact that A. she's watched all her anime and B. she's bored.
Monster Kid was one of the results of Alphys' testing; he gained arms at the cost of his sight, and his other senses were improved after that.
Muffet died long ago, and came back as a ghost after her dust was injected with Perseverance. Apparently that works better than Determination at bringing back dead people.
After Alphys was exiled, a call for the new Royal Scientist came out. Sans' brother, Papyrus, had recently died, but he'd managed to save his SOUL in one of the SOUL containers. After hearing the call, he applied, and was accepted. Using the materials he had, he built a container for his brother's SOUL, unintentionally causing him to become sentient again and creating a robot body for his dead brother.
Grillby is dead. Fuku took over his restaurant in order to keep his memory alive.
Lez and Bewoulf came from out of nowhere and asserted themselves in Snowdin Town, just like the original Sans and Papyrus.
- Switch ran away from her AU with Lez. They met up with the Irritating Cat and became the Meme Squad.
- Bewoulf can also leave the AU. He just doesn't want to.