For the 2nd season of Underverse, see Underverse Season 2.
Let the experiment do as it pleases, follow its game... Be the hero or the villain of its own calamity until I decide when to start Phase Three.
~ XGaster explains the first part of his plan to Ink

Underverse Season 1 is the first season of Underverse, created by Jakei95. Trouble begins to brew when half of Sans's soul is stolen by a thief from an alternate universe. Once Sans begins suffering side-effects with only half a soul, he, Ink!Sans, and a whole group of Sanses have to stop him and Cross!Chara, to discover out the true meaning of the X-Event.


Sans wakes up in a strange universe to meet Cross!Chara, who demands that he should keep him in his universe. He refuses, and Cross!Chara takes half of Sans's soul and runs off once Ink!Sans arrive to stop him. They absorb the soul, and make a deal with Nightmare!Sans to cause suffering whenever they go to other universes. Ink recounts to Sans that he met Cross in a new AU, and discovered he was the sole survivor of a Genocide Route without reset possibilities. The two became friends, but tensions rose when Ink told Cross that he couldn't bring back his world. Soon after, Error!Sans took Cross's soul, and though Ink protected Cross from Error's attack, Cross ran away in order to take Sans's soul.

Sans decides to stay rather than fight. However, after he has difficulties in a volleyball game, he chooses to join Ink, and tells his Frisk to keep watch for him. The two arrive in Underfell as Cross marks areas to take back to Xtale. Underfell!Sans attempts to mock and resist his efforts, but is soon defeated. Ink and Sans both arrive, and the two battle against Cross and Underfell!Sans, who has fallen under Cross's control. After Sans distracts Cross, Underfell!Sans is freed from his control. Cross!Chara forces Cross to escape being killed by Underfell!Sans, and the two flee with Snowdin's code.

Sans is given a tip to defeat Cross by Core!Frisk, and Underfell!Sans joins up with him to avoid severe punishment from his brother. After Ink talks with Error regarding recent events, Dream!Sans spies on XTale to figure out the next AU Cross plans to target. Cross!Chara isn't happy that they haven't gotten a human soul and attempts to take over Cross's body, but he is narrowly stopped. Cross heads to Underswap next, and discovers that this universe's coding reminds him of his own. Conflicted, he continues to work for Nightmare, but thanks to Core!Frisk's advice, he is swiftly beaten and Sans gets his soul back. However, Cross!Chara absorbs the soul of Underswap!Chara and teleports Sans and Underfell!Sans out of Underswap to torment Underswap!Sans, Underswap!Papyrus, Underswap!Chara, and Ink.

As the three of them suffer from X-Event!Chara's constant overwriting, he demands the strange vial Ink has been protecting. When X-Event!Chara is refused, he uses the Underswap cast as pawns to attack Ink. However, they inexplicably break free of Overwrite. Underswap!Sans and X-Event!Chara battle each other, but when Underswap!Sans threatens X-Event!Chara with a Gaster Blaster, he is overwritten and forced to attack. Underswap!Papyrus gives up because of his inability to stop them. He recounts his good memories, which allows Dream!Sans to return Sans and Underfell!Sans to the fight. X-Event!Chara confides with Sans that his timeline is "not exactly as it should be", and attempts to convince him to rebel against Ink. However, he is stopped by Nightmare, who mortally wounds Underswap!Chara and retreats with X-Event!Chara. Underswap!Papyrus decides to stay in his destabilizing timeline while the others escape to Outertale.

Meanwhile, during Error's dream, he comes to suspicion of Ink's actions and learns more of the X-Event. Once he enters X-Tale to see the code that Cross and X-Event!Chara have gathered, he blames Ink and calls their truce over.



Image Characters Summary
ClassicSansUnderverse.png Sans The main protagonist, Sans lived a peaceful life until Cross!Chara took half of his soul. While he does get his other half back, he still has to face X-Event!Chara.
InkSansSeason1.jpg Ink!Sans Ink!Sans may be happy-go-lucky, but when he's serious, he uses his paintbrush to summon various objects to defeat his foes. He helps the other Sanses throughout their journey, but he may be lying about his true intentions...
UnderfellSansUnderverse.png Underfell!Sans After an encounter with Cross, Underfell!Sans is forced to join up with Sans and Ink to hide away from his brother for the time being.
UnderswapSansUnderverse.png Underswap!Sans Underswap!Sans's new life on the Surface is ruined after Cross invades his AU. X-Event!Chara torments him with Overwrite, which causes him to retaliate and join up with Ink.
CrossUnderverse.png Cross Cross is the anti-hero of Underverse, conflicted in most of his actions. Cross desperately wants to bring back the world he lost by taking code from other AUs, but in reality, Cross!Chara is the one pulling his strings.
XCharaProvisional.jpg X-Event!Chara After absorbing 95% of Underswap!Chara's soul, Cross!Chara regains the power to manipulate, control, and overwrite the code of AUs. He desires to take revenge for his suffering at the hands of XGaster.


Image Characters Summary
ErrorSansUnderverse.png Error!Sans Error!Sans is the deuteragonist of the series. While he did take Cross's soul, he didn't destroy it because of the truce he and Ink made. He wished the truce would end, something that would happen when he discovers something in X-Tale.
NightmareSansUnderverse.png Nightmare!Sans As the brother and opposite of Dream!Sans, Nightmare's goal is to spread negative feelings through the multiverse. He makes a deal with Cross, giving him the ability to access any AU he wants as long as he causes suffering in the process.
DreamSansOriginal.jpg Dream!Sans While Ink refuses to let him help find Cross, Dream does give the crew vital information by spying on the enemy. He arrives on the battlefield to fight his brother, Nightmare!Sans.
CoreFrisk.jpg CORE!Frisk Takes characters with no timeline to call home to the Omega Timeline, a safe place that Error can’t reach.
FreshSans.jpg Fresh!Sans A parasite that has taken over a Sans’ body and is incapable of feeling emotions. He has been enlisted by Ink to guard XTale, being promised “the funniest thing in the multiverse” in return.
XGasterSE1.jpg XGaster A mysterious observer lurking in the shadows, watching everything unfold. His sinister intentions go unnoticed by most of the cast until it’s too late.


Image Characters Summary
UnderverseFriskSE1.jpg Frisk Comes from a “fake pacifist timeline” of Undertale. They are currently living on the surface with their friends, having a picnic. They are worried about what is going on with Sans, but are allowing him to journey with Ink.
UnderswapChara.jpg Underswap!Chara Comes from a post-pacifist timeline of Underswap. They’re starting a happy new life on the surface, but it soon comes to a screeching halt after Cross attacks their timeline.
UnderswapPapyrus.jpg Underswap!Papyrus The Papyrus from a post-pacifist timeline of Underswap. He is moving to the surface with his brother and friends. His days of peace soon come to an end after Cross attacks his timeline.
UndernovelaAsgoro.jpg Asgoro The Asgore from Undernovela. He appears in Error’s dream, interrupting Sin and Toriel’s wedding before he learns the news that his child has been kidnapped.
XAlphysSE1.jpg XAlphys The Alphys from XTale. She has been waiting in the Doodle Sphere with XGaster, and has been sent to quarantine the timelines affected by the X-Event.
Безончик.png Killer!Sans Nightmare's subordinate, pulled from his respective timeline to aid him and X-Event!Chara in their plans. He harbors a grudge against Chara after their alternate universe self forced him to kill.
OutertaleSans.jpg Outertale!Sans Comes from a timeline of Outertale. He has not met the Frisk of his timeline yet, and is just living a peaceful life with his brother. However, he soon finds sinister intruders and attempts to defend his timeline from them.


For non-revamped episodes prior to 2018, please refer to each of the episodes for more information.

Video Episode
TRUCE_-_Underverse_SE1_Prologue Truce
UNDERVERSE_0.0_REVAMPED_-_By_Jakei Underverse 0.0
UNDERVERSE_0.1_REVAMPED_-_By_Jakei Underverse 0.1
UNDERVERSE_0.2_REVAMPED_-_By_Jakei Underverse 0.2
UNDERVERSE_-_XTRA_SCENE_1_REVAMPED_-_By_Jakei Underverse Xtra Scene 1
UNDERVERSE_0.3_Part_1_REVAMPED_-_By_Jakei Underverse 0.3 Part 1
UNDERVERSE_0.3_Part_2_By_Jakei Underverse 0.3 Part 2
UNDERVERSE_-_XTRA_SCENE_2_By_Jakei Underverse Xtra Scene 2
UNDERVERSE_0.4_-_END_OF_SEASON_1_-_By_Jakei Underverse 0.4
UNDERVERSE_0.4_-_EPILOGUE Underverse 0.4 - Epilogue


  • Most of the videos related to Underverse on YouTube have comments disabled due to the amount of fan requests for AUs to appear in this series, not knowing that the AUs were selected already not even halfway though the series.

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