Timeline / Underverse

• In the events prior to XTALE/Underverse, a growing number of alternate universes in the multiverse are left abandoned by their creators due to lack of motivation, opening a gap for Error!Sans to demolish said universes. Ink!Sans, very wary of the destruction of these universes, and in fear of being forgotten, negotiates with Error for a ceasefire, where both of them can no longer destroy or create anything within the multiverse.
  Error!Sans: "NO MORE CREATION, NO MORE DESTRUCTION"
• In one of the Genocide timelines in the original universe, Sans miraculously manages to kill Frisk while they were trying to deal the final blow, causing their timeline to glitch into a Pacifist timeline. This results in him and Flowey remembering everything from the previous timeline, but for the rest of the monsters, including Frisk, forgetting the past timeline, making Sans the owner of this timeline. Sans realizes the power he has over the monsters and Frisk, but realizing the damage he may have brought, he confesses everything to Frisk, and the two of them (including allegedly Chara) confront Flowey and eliminate him.
  Flowey: "The odds against you were 9 million to one...but you finally broke your timeline!"

XTALE

• Desperate to continue saving dying universes, Ink ventures into an endangered universe to prevent the universe's Gaster from destroying all that he had created by showing him the multiverse. This Gaster feels motivation to continue to venture forward with his own universe, for his and his childrens' sake.
• TIMELINE I: Now rechristened as XGaster, he begins his experiment by giving his children, XTale!Frisk and XTale!Chara, a family and friends to bond with. However, his perfectionism starts to show, and he reluctantly overwrites this timeline altogether.
• XGaster takes an opportunity to showcase his unique ability to Ink: the OVERWRITE button, a power that grants the user the ability to change anything. Unwilling at first, Ink decides to allow XGaster to continue this experiment, knowing that it would not affect the truce that he made with Error.
  XGaster: "OVERWRITE. The power to completely change anything, the reality itself of an Alternate Universe. (...) It won't break the truce you made with that person. I...want to find the best for them. Please, I need you to understand...
• TIMELINE II: XGaster's children start to get annoyed by the repetitiveness of the timeline, having to repeat their greetings with their friends and family. Eventually, XChara bonds with XTale!Asgore, while XFrisk shares a connection with XTale!Sans. This euphoria upsets XGaster, prompting him to kill XAsgore and XSans in order to feel a sense of happiness. With nothing left to do, and with little resistance from XChara, XGaster overwrites the timeline.
  XGaster: "EVOLUTION REQUIRES SACRIFICE."
• TIMELINE III: By far the shortest timeline to be overwritten. XGaster tries to replicate the features of another alternate universe, Underswap, but is dissatisfied with the results. XChara calls him out as an "insecure old man".
• TIMELINE IV: Still hoping to please Ink, XGaster attempts to start a Genocide Route with XFrisk, curious if his determination will allow him to ignore XGaster's orders. The route is sabotaged, when XGaster's assistant XTale!Alphys sneakily reveals the truth about the timelines to XTale!Muffet, which leads her to convince XChara to rebel against XGaster. He does so by utilizing the first instance of the RESET button for the first time, angering XGaster due to the fact that the RESET button will allow other timelines to coexist.
  XTale!Muffet: "STOP HIM NOW, GODDAMMIT!!"
• TIMELINE V: Not wanting to leave his children unpunished, XGaster causes everyone in the XTale universe to forget XChara and XFrisk, invoking their ire against their father. They attempt to get XAlphys, their father's assistant, to spill the beans, but are put on a hold when XTale!Undyne stops them in their tracks. After hearing about their situation though, XTale!Undyne agrees to put the both of them under her belt for training, although XFrisk shows signs of weariness to go against their father. XUndyne and XChara confront XGaster directly, who reveals he had already eliminated XAlphys for her deceptive behavior, and orders XUndyne to hand him his child back. When she refuses and takes him down, he ends up overwriting XAlphys and the other anomalies from the previous timelines to take the two of them down.
  XAlphys (implied to be XGaster speaking through her) to XTale!Undyne: "Your hopes and dreams do not work in my reality."
• TIMELINE VI: Weak yet still willing to fight his father, XChara tries his hardest to take down his father's amalgamates, but being unable to kill them, he's immediately taken down and half of his determination is swapped out for XGaster's perseverance, granting him the power of the OVERWRITE button and kick-starting the X-Event experiment.
  XGaster: "CHARA IS THE STRONGER ONE"
• TIMELINE VII: Although disappointed with his newly obtained power, XGaster feels satisfied to have a fragment of determination within his soul. As his X-Event prototype repeatedly kills XFrisk though, he understandably sees this timeline as a waste of time, and is about to eliminate XFrisk altogether before his X-Event prototype convinces him that without XFrisk, their souls are not satisfied. With this, the X-Event merges together within XFrisk, who now serves as a vessel for the X-Event's soul.
  X-Event!Chara: "YOU want him back too. OUR soul is not satisfied and you know it."'
• TIMELINE VIII: With both humans now inhabiting a single body, the X-Event is taught by XGaster how to use the OVERWRITE button. The X-Event soon discovers XTale!Mettaton discarded within the data compilations, and manages to bring him to life. XGaster is immediately amused that his experiment possesses creativity, but despite this, he orders the X-Event to destroy XMTT, invoking the wrath of X-Event!Chara and causing XMTT to nearly kill him.
  XMTT: "I'M TIRED OF YOU."
• In fear that the X-Event and his creations will kill him for everything he has done to them, XGaster asks Ink to carry half of his soul in a vial and stay far away until he begins the "third phase" of their game, explaining that he'll be able to handle himself with XChara's determination.
  XGaster: "FOR THE FIRST TIME IN A WHILE, I FEEL SCARED. (...) I AM NOT DONE YET. THEY CAN'T DO THIS TO ME."
• TIMELINE IX: With only XChara's determination by his side, XGaster is barely able to do anything but stare into the outside world. In an act of desperation, the X-Event tries to tell XTale!Papyrus about XGaster's evil acts, but this causes him to lose faith in not only XGaster, but the X-Event too. XGaster's ruthless manipulation causes the X-Event to reset the timeline entirely.
• TIMELINE X:
  • The X-Event, after resetting the timeline, is discovered by XTale!Asriel, who he decides to greet them with alongside XAsgore, XTale!Toriel, XPapyrus, XSans, XGaster, and XAlphys. They show little interest in playing with the rest of the monsters, and are desperately suicidal.
  • After breaking the barrier due to XGaster's manipulation, the X-Event tries to use the OVERWRITE button on humans to try to attack them as a way to provoking XGaster into trying to use his OVERWRITE button, however the will of their "friends" ends up ruining their plot and only enforces heavy surveillance by the royal guards, which XSans ends up joining alongside his brother.
  • Ten years after their first attempt at overwriting humans, the X-Event confesses to XSans their current situation and how he feels trapped being monitored by a royal guard. XSans confesses that him joining the royal guard was to allow him to be closer to his friend, offering a sign of hope to the X-Event's goal.
  • While transporting the X-Event around town, XUndyne takes the X-Event "captive", prompting a chase down to get their friend back. In the midst of this however, XSans is overwritten briefly and nearly goes through with killing the X-Event only to be stopped by XPapyrus at the last second.
  • The next day during a peace ceremony, XSans is overwritten once more to kill the X-Event again with his Gaster Blaster, but XGaster promptly shuts him off. In a fit of anxiety, he tries to confess to XPapyrus, XMTT, and XAlphys about what's going on, but XGaster ends up resetting the timeline, causing further damage to XSans' psyche.
  • Later, the X-Event shows XSans the original universe and how it differs from the current situation in XTale, explaining that if they don't kill XGaster, they won't see a future where they can make mistakes and create more timelines, and where they'll be the one in control. XSans does not agree with the X-Event's motivations, prompting a fight against the two where the X-Event finishes him off with the OVERWRITE button. Feeling sorry that he ruined XSans' clothes, the X-Event declares that once this timeline is overwritten he'll nickname him Cross, and that he'll create something better than what XGaster has.
  • Now fully recovered from his previous resetting, XGaster ends up stopping the X-Event in its path and resets the timeline itself, which to his dismay revealed his sole determination half and with the implications that the X-Event is the only one with control of the OVEWRITE button. With this knowledge, X-Event!Chara suggests to his brother to bring back their friends' memories and then to kill XGaster.
    X-Event!Chara: "We'll bring our friends' memories back and then...WE'RE GOING TO KILL XGASTER."
  • Displeased that Cross is still unwilling to accept the X-Event's offer, XUndyne and XPapyrus end up beating Cross down, to keep him from potentially interfering in their take down of XGaster. Cross survives, and decides to take things into this own hands.
  • During the confrontation between XGaster and the X-Event, Cross intervenes and kills the rest of the monsters, including his brother XPapyrus, in order to take the power to overwrite for himself. X-Event!Chara tries to take over Cross' body to reunite with X-Event!Frisk, but Cross takes his vessel out with his knife, resulting in X-Event!Chara being stuck within Cross. Only then does Cross realize that the X-Event's powers are incompatible with his monster soul, making him unable to bring back his friends in the process, and causing him to mentally break down.
  • XGaster survives the ordeal, now outside his own universe. He would later be greeted by the Original Universe's Gaster who prompts him to give up, explaining that the bright future he is chasing will lead him to failure. He dismisses the claim, unwilling to accept the consequences of his actions.

UNDERVERSE (Season 1)

• While busy in the Doodle Sphere, Ink hears water droplets coming from the XTale universe and decides to reenter the universe, only to find out that the only inhabitants left are Cross and the spirit of X-Event!Chara. The two end up bonding together, though Ink hides the soul fragment of XGaster from Cross. X-Event!Chara takes this as an opportunity to skim through the many alternate universes that Ink was observing.
• Later, Core!Frisk tries to invite Cross into their Omega Timeline, to which he refuses because he still believes that his world could be saved. During their next meeting, Ink blatantly tells him that his world cannot be restored, which only worsen Cross' mental state.
• Not long before the events of UNDERVERSE 0.0, Error!Sans takes notice of Cross and runs off with his soul, much to Ink's disapproval. This causes Cross to be corrupted and only lingering on X-Event!Chara's determination..
• UNDERVERSE 0.0: Sans wakes up in an empty void where X-Event!Chara/Cross tells him what he is and requests to stay in his universe. When Sans doesn't assent, X-Event! Chara/Cross takes half of his soul in order to stay within his universe, only to be intercepted by Ink, who manages to chain X-Event!Chara/Cross up with his paint ability. When he requests that they give Sans' soul back to him, X-Event!Chara/Cross ends up escaping his grasp and return to their universe out of desire to rebuild their own.
• UNDERVERSE 0.1:
  • In the aftermath of 0.0, Sans agrees to hear more about Cross from Ink, and learns that he was the lone survivor of what was a Genocide Run, without any RESET ability possible. After hearing his story, Sans opts not to join Ink in search of Cross, and desires to stay with his friends in his own universe.
  • Cross agrees to X-Event!Chara's plan to rebuild their own universe, and absorbs Sans' soul fragment, allowing Cross control over the body. Later, while discussing how to traverse the multiverse, Cross goes berserk over being unable to save his own universe, gaining the attention of both Nightmare!Sans and Dream!Sans, the former manages to obtain a deal for him to cause pain and suffering in exchange for traveling throughout the multiverse, and the latter warning Ink!Sans' about Cross and Nightmare's deal.
    Nightmare!Sans: "Wherever you go, I want you to hurt somebody, but not physically. You know what I'm talking about."
  • As Sans enjoys a picnic with his friends, he begins feeling unwell, and later realizes a subtle X over his soul, and he ends up leaving the picnic and tries to call out to Ink. Frisk, who was chasing Sans, is concerned over the situation, and after realizing that half of his soul is missing, Frisk is reluctant to break their promise and RESET their timeline, to which Sans disagrees. Ink manages to hear Sans' plead and enters, to where he and Sans explain the whole issue to Frisk. Sans asks Frisk to hold him until he returns from getting his soul back, as he and Ink venture off to finding where Cross has been transported to.
• UNDERVERSE 0.2:
  • As Cross enters a pacifist timeline of Underfell thanks to Nightmare, his plan of obtaining portions of this timeline begins, and is merely interrupted by Underfell!Sans. Ordering him to retreat and accept his ownership of his universe, Underfell!Sans attacks Cross in order to stop him from taking Underfell over. However, Cross proved fierceful, gaining the upper hand against Underfell!Sans until Sans and Ink manages to find out his location. Not wanting to accept defeat, he immediately infects Underfell!Sans under his belt.
  • As the two side clashes over each other, Nightmare witnesses the assets of Underfell's Snowdin being transferred away. Sans manages to keep Cross distracted while Cross' influence on Underfell!Sans fades away, and he ends up leaving as they obtained the core code of Underfell. While Underfell!Sans and Sans gloss over the loss of a portion of their universe, Ink is taken captive by Error.
• UNDERVERSE XTRA SCENE 1: Core!Frisk makes a surprise visit to Underfell, in order to give him advice on how to take down Cross, and feels sorry that he was involved in this thanks to them (either referring to Cross or Ink). Error!Sans, whom he has taken Ink hostage, reminds him over the truce that they made between each other, threatening to take action should he find out the true secret behind the X-Event on the account that he broke their truce. After letting him go, Ink relies on Dream to tell him the next AU that Cross is wanting to target.
• UNDERVERSE 0.3:
  • Feeling discontent with the failures Cross dealt in Underfell, X-Event!Chara tries to take over control over his body, which Cross puts an end to. After a minor skirmish between him and Nightmare, Cross is brought over to Underswap, and notes a distinctive familiarity in this timeline's code and his own universe's code.
  • Underswap!Sans agrees to help Ink, Sans, and Underfell!Sans to find Cross, where upon finding him Sans and Underfell!Sans put their plan into use, and successfully Sans' soul is unified once more. Taking advantage of this, X-Event!Chara takes out 95% of Underswap!Chara's soul in order to reactivate his OVERWRITE button and allow the transfer of various assets of this timeline into his own universe. In the process, he throws Sans and Underfell!Sans into the XTale universe and Nightmare ends up trapping Ink from doing any harm.
  • With the OVERWRITE button once more in use, X-Event!Chara does a "demostration" on Underswap!Sans, Underswap!Papyrus, and Underswap!Chara on the effects of the OVERWRITE button, which interests Nightmare on the topic of pain and suffering. In the midst of this, X-Event!Chara attempts to ask Ink to give him the vial that he was tasked to protecting, but the reversion of US!Sans and US!Papyrus to their normal states due to the incomplete button stops him in his tracks, and he is forced into continuing to serve his portion of Nightmare's deal.
  • After being thrown into the XTale universe, Underfell!Sans and Sans are forced to wait for Dream to signal a positive feeling in Underswap. Once a signal is reached, of which Underswap!Papyrus is giving up on their timeline yet happy that they made good memories, the three of them take out X-Event!Chara and Nightmare.
  • Growing desperate, X-Event!Chara tries to mediate with Sans over his alleged broken timeline, offering him to strike down on Ink before being interrupted by Nightmare, who ends up killing Underswap!Chara. The two of them flee the now corrupted timeline, and all except Underswap!Papyrus and Underswap!Chara end up leaving to Outertale.
    X-Event!Chara: "You only wanted to stop the creation of timelines due to your human's Resets, and then all of this happened. You're still suffering even with a "happy ending." (...) Your timeline is not exactly as it should be."
• UNDERVERSE XTRA SCENE 2:
  • While watching for his favorite show to start, Error!Sans is startled by the appearance of Ink in his hideout place. While there, he exposes his plan of taking him down because of the truce they made, but before Error could react, Ink reminds him that his show, Undernovela, is about to start.
  • The synopsis for this episode of Undernovela is that Frisk had been kidnapped while Asgoro and Sin were fighting over the latter's marriage of Toriel, forcing the both of them to team up in order to find their child. The kidnappers? Cross and X-Event!Chara. Immediately taken aback by their appearance, Error is stunned when Ink enters the universe itself and uses XGaster's powers to overwrite Sin and Asgoro, eagerly happy that Error has joined in their game.
  • Error wakes up from this nightmare he had witnessed, and in retaliation ties up the entire Doodle Sphere and threatens to destroy it all for Ink. After entering XTale and being rudely greeted by Fresh, he notices the stolen assets from the other universes, implying that the X-Event's true purpose was to create a new universe, a violation of the truce he made with Ink. With this, he ends their so called truce, and plans out his victory against Ink.
    Error!Sans: "OUR TRUCE...IS OVER."
• UNDERVERSE 0.4:
  • Having glossed over the events that has happened in Underverse, XGaster asks his assistant XAlphys to analyze the damages caused by the X-Event and quarantine them. XAlphys goes over to the Underswap pacifist timeline that X-Event!Chara/Cross were in, where Core!Frisk moarns the death of Underswap!Papyrus and Underswap!Chara. XGaster is infuriated by their destruction of the Underswap timeline, and XAlphys comphrends his loss as he sends the timeline into quarantine. Core!Frisk is surprised and curious over the XTale's people intentions. As XAlphys enters the pacifist timeline of Underfell that Cross visited, she is threatened by Underfell!Asgore to speak up, but unwilling to do so, she ends up summoning XMTT and ask him to kill of the rest of the inhabitants as she places the timeline under quarantine. Witnessing this, Core!Frisk warns Dream about this implication, and Dream fears that XGaster might end taking down Sans' own broken timeline
  • Injured from their battle against Underswap!Sans and co, X-Event!Chara is berated by Nightmare for holding back on their mercy, of which he knows that his mercy is what allowed XGaster to psychologically abuse him into generating the biggest negative feelings in the entire multiverse during the time the truce was in place. Still impressed by his talent though, he orders X-Event!Chara to work really hard for him in a genocide timeline, but X-Event!Chara refuses and orders Nightmare to send him off to where Ink is and where the vial is. He responds by nearly killing X-Event!Chara off before deciding to keep him alive under the protection of Killer!Sans, where he knows about the atrocities that X-Event!Chara has committed against him due to his status as being part of an alternate timeline of the original universe.
    Killer!Sans: "Sometimes we can know what is happening in other timelines that belong to the same Universe. We are just slight variations...Alternate Timelines, for short. An "anomaly" from a main Universe, changed forever by forced decisions. (...) Congratulations, Alternate Universe trash. You have learned something interesting today."
  • As the three Sanses talk about their past battles and how they were helped from an "outside force", they note that Ink has gone missing once again, and Sans ends up traversing Outertale in order to find his location. Meeting up with Outertale!Sans, they attempt to find where Ink has gone off to, but ends up encountering Killer, Nightmare, and X-Event!Chara, all of whom are forcing the latter to consume a monster soul much to his disapproval. Error intercepts their meeting and demands to talk to Nightmare over the location of Ink, only redirecting them to Sans and Outertale!Sans, to which Outertale!San sacrifices his life for Sans in order to alert the other Sans to no avail.
  • With Error causing a commotion among the Outertale universe, Ink notices this and arrives to investigate, where Error threatens to destroy everything in the multiverse due to having breaking their truce. Ink doesn't budge, and is eager to bring XGaster back in order, leading to a fierce battle between him and Error, as well as X-Event!Chara, over the vial.
  • Underswap!Sans, Underfell!Sans, and Sans confront Ink over his desires to protect the AUs, where Ink explains that what he's doing will only affect a small fraction of the multiverse willing for everything to be restored back to normal. With nothing else stopping him, Ink drops the vial and calls forward the restoration of XGaster. Error throws his own punches by tearing apart the entire Doodle Sphere, exclaiming that he's not interested in their game.
  • Because of Error's disapproval of their game, XGaster entices Ink to lock him up in his own Anti-Void while taking back his other perseverance half from Cross's/X-Event!Chara's soul. X-Event!Chara plan of obtaining the other half of the OVERWRITE button were demolished, and he ends up dying without a soul in sight. XGaster then proceeds to wipe out Underswap!Sans and Underfell!Sans, returns Sans back to his own timeline, and feeling a bit sorry for XChara, rejuvenates his soul and hopes that he uses his Determination on his behalf. Knowing that it would be harder for XGaster to persuade him to join, he brings back Cross and gives him the choice to join him or not, before evading and will be waiting for him.
    XGaster: "We will be waiting for you, Cross."
  • As Cross is left behind from XGaster, he witnesses Dream getting brutally torn by Killer for attempting to attack Nightmare, which enrages him to fight back against Killer, allowing him and Dream to escape to the Omega Timeline, where Core!Frisk is waiting for him.
• In the aftermath of 0.4, XFrisk wakes up his brother XChara from his slumber, claifying that XGaster is waiting for them to appear before him.
  XFrisk: "...Come on, brother! They're waiting for us."

UNDERVERSE (Season 2)

• Owners:

• UNDERVERSE 0.5: