As Frisk left the underground with the memories of the friends they had made and adventures they had, things changed. Since King Asgore was no longer around, Toriel has returned as the rightful Queen of the Underground. Papyrus is now living his dream as he now is the head and only member of the royal guard. Meanwhile, Alphys and Undyne conducting research for new ways to escape the Underground without the use of souls. As for Sans, he's still the lazy royal sentry in Snowdin. As for the human souls, they didn't disappear but just wandered in the underground later to be caught and brought to Alphys to aid in some side-project of hers.
Things were peaceful for a while and everything was running smoothly like always but nothing lasts forever. As previously stated, Alphys was working on a side-project that would hopefully extend the monsters knowledge of Souls. The side project's main goal was to master the powers that the fallen humans possessed and understand their traits.
It would seem harmless enough but one accident changed everything. She had one machine that was used to aid in her research. It was connected to the Core since it needed tremendous amounts of power, It one day blew up and had some weird effect on the Core. Everyone in the underground has gotten amnesia, except Alphys and Flowey somehow, and everyone merely presumes everything about themselves.
Not long after, another human fell into the underground searching for their friend Frisk but was not aware that Frisk left the underground long before they had fallen into the underground in search of their friend. They passed through, looking at all the confusion. They were trapped there for some time but found a little note telling them how to leave. With the help of the instructions on the note, they left the underground with a monster soul they got from a newly dead Jerry. They got to the surface and reunited with their friend. They exchanged stories about their separate adventures in the Underground. Frisk, having thoughts of them possibly being the cause of this change, dove back into the underground with their mind set on bringing it back to the way it was before.
The 3 Main routes of the AU is True Hero Route, Neutral Route, and Erase Route...
This route can be achieved by lacking any of the following requirements:
- Friendship with any of the Soul Guardians.
- A fight with any of the Hostile Bosses.
- Friendship with Docile Bosses
- Any monsters you lacked to remind or you chose to erase some monsters.
- Any unfinished Alphy's Quests.
Different endings under Neutral Route
Regular Erase Route
This route can only be achieved if you complete the following requirements:
- Erase all Hostile and Docile Bosses.
- Erase all monsters.
- Threatened Alphys in her lab.
- Unlock Boss J's fight
- Kill all Soul Guardians.
- Regular Erase Route
Doing this will obtain you the regular Erase route. Chara will proceed to say they are happy that you have returned so they can finish the job. They will then proceed to erase the world leaving themselves, you, and your soul. When choosing to re-open the game, you just have to wait for 5 minutes and Chara will give you the same offer as regular Undertale. After getting this ending, the next True Hero Route you do will be a Neutral route. Unlike regular Undertale, you can avoid this by resetting.
True Erase Route
This can only be achieved by completing the following with the regular requirements:
- Erasing Flowey
- The tapes in Alphy's lab
- Destroying all Golden flowers.
- Taking Charas True Knife and Heart Locket.
Chara will appear at the end of the game but they are faded. They proceed to then explain their original plan when frisk first fell into the underground. Then begin to say that now that they've got no control over Frisk, they can't make them choose but suggests for them to reset.
Choosing reset will send you back to give you the Corrupted Hero route and keeps it that way.
Choosing Erase will erase everything in the underground. After this, The game is no longer playable.
True Hero route
Main Monster Characters
"The overworked and forgotten scientist"
After everyone forgot who they were, she isolated herself in the True Lab, that hasn't changed that much. She begins beating herself up about making another huge mistake and emotionally torturing herself about it. This self-hate was ignored after she decided to peek into her upstairs lab and saw Undyne who already lost and arm and a leg, constantly yelling threats. Alphys was tremendously hurt by seeing Undyne like that and immediately set her mind to fixing the machine so she can fix her mistakes. She won't hide her mistakes this time.
As previously shown, she is more stressed and depressed than she was in the normal Undertale. All her memories are intact but focus more on her mistakes that fuel her to keep working. She sits in her lab working 24/7 barely even stopping to eat a snack. She is on the Neutral side since she has never left her lab since she saw Undyne. Alphys plays a more important role here and has a line of quests for you to do when you meet her.
Papyrus aka Boss P
"The best and only chef in the Underground"He is now goofy and Nerdy chef that sings songs about cooking. He lives in the Skeleton brother's old house still and is now operating was formerly known as Grillby's, Papy's. He is less social with most monsters unless they're his customers or Boss P. He hates Boss S and Boss T due to the fact they do tend to rob his restaurant's food supply overnight. Upon waking up he ends up outside the Libarary and presumes her must be a book lover. He only remembers that he loves to cook. He will be one of the more passive monsters. He can and will help you pass through snowdin if you help him.
Mettaton aka Boss M
"The robotic, anime loving, local of snowdin"When they first wake up they are surrounded by things in Alphy's Lab and notices the dress on from the Undertale the Musica part and presumes they are a female. So she is now a shy, nerdy, and geeky person who loves anime. She lives in Alphy's Lab and hangs at Papy's quite often. She hates Boss N, Boss T, Boss S and Boss U and one of her only friends is Boss P. Her only memory is that she knows someone who is geeky and nerdy. She wakes up at Alphys' lab and presumes it to be her home. She is one of the passive monsters and at first will be quite skeptical of you but will help you largely in later game if you do decide to befriend her
Sans aka Boss S
"Boss T's Slave"(WIP)
He woke up in Judgement Hall hall with the only memory of someone very, very evil. He is now insomniac terrorist who can't make his own decisions. He is always working for Boss T and he remembers a person who wants to kill everyone and Erase the world. However, he does not remember he can use or even has Gaster Blasters.He woke up in Judgement Hall and is on Boss T's side.
W.D. Gaster aka Boss J
"The first and original, forgotten scientist"(WIP)
"The dead and forgotten king"(WIP)
Toriel aka Boss T
"The literally killer Queen of the underground"
She is now the crazy killer queen who wants everyone dead and shows no emotions to anyone or anything. She constantly abuses her followers and forces them to do things for her with the lie of her helping them get what they want.The one thing she remembers is someone killing innocent children and presumes it to be her and to support that thought of hers as she woke up in the Human Soul's coffin room. NShe works on the murderers side or her own side. She can only be found in the throne room and doesn't leave it.
Soul Guardians. (The Fallen Humans)
Though the Underground is filled with the confused monsters, the 6 human souls have risen from the grave. When Frisk left the underground, the 6 human souls were free to roam the underground only to be captured once again for Alphys'sideproject. Their souls were once again contained but then freed when the machine blew up. This time, their souls wandered back to their bodies. They were originally rotting but Alphys also has seemed to have done something to the souls. Attempting to inject Determination back into their bodies somehow reversed the damage the rotting has done. As soon as they woke up, they roamed around working together to see what has happened. They immediately agreed to split up and help certain zones of the underground as soon as they saw the confusion that can be seen around them.
But they faced one problem, only 6 of them and a huge underground to keep watch of. Their solution was to divide themselves into 3 pairs and that being:
- Team Ruin'din- consisting of Clara and Jason.
- Team Danger Falls- consisting of Katherine and James.
- Team Hot Core- consisting of Amanda and Kyle.
They paired up accordingly to whos near who. They bunch may seem to like each other but not all of them are friends. A few actually hate each other but do their best to work together peacefully since they are all working for the same cause. They all work for the same cause but some want it done differently so beware of them.
Patience aka Clara Soul Guardian
A 7-year-old girl that was the first human to fall into the underground. Clara fell to the underground while searching for her mother who was doing research about the flora that can be found on Mount Ebott. While searching in the darkness of the night, she fell into the underground and was later found with toriel but was killed later on. Like previously stated, she was assigned to the ruins and fixes it up to the best of her abilities. She chooses to wear the outfit she made for herself using Toriel's clothes and adjusting it so it would fit on her.
Clara can only be found 1/2 of the way in the ruins and will not have any aggression towards you but beware of your actions before you meet her. Being the soul of patience, she won't immediately if you meet her after erasing a few monsters but if you meet them after erasing half of the monsters in the Ruins, she shows signs of being upset but does nothing. Leaving 1/4 of the monsters in the ruins then meeting her, it will cause her to come after you and will initiate a fight. She is very weak and doesn't deal that much damage. She is level 3 and she attacks using blue and white knives. She may even use 2 healing items at max if you don't finish her off within 5 turns. The items will only heal 1/3 of her health.
Lines when they are killed
- First one to be killed- "Oh dear... I'm sure this is a mistake... I know you didn't mean it! I'm sure it was an accident! Just go forward and save the underground! Go to the other soul guardians for help!"
- Neutral- "Oh my... I-I expected this... I know you can be better! Use my soul and free them! Please..."
- Erase- "*Sniff* I knew I should have killed you off.... I thought if I waited.... you'd stop and change. I was patient with you and look where it got me.... I tried to be patient with you but... I-I should have stayed at home and waited for mommy to come back home... I would have never fallen down here. I wouldn't be the one to make this mistake.... *Collapse*"
Bravery aka Jason Soul Guardian
Perseverance aka Katherine Soul Guardian
Integrity aka James Soul Guardian
Justice aka Kyle Soul Guardian
Kindness aka Amanda Soul Guardian