Zephyrtop is a spin-off from two AUs: Zephyrtale and Undertop. It focuses on Zephyrtale Gaster and Undertop Gaster, an astronomer and a ringleader from two completely different AUs with two completely different roles. They met through unconventional circumstances, became best friends, fell in love, and are now husbands in their own AU.
Undertop Gaster did not always possess the title of ringleader. The first iteration of his universe didn’t even have a circus to begin with, and was no different from that of the classic Undertale. Having spent many years working as a royal scientist under his friend Asgore’s employ, Gaster was often absorbed in his work, studying the boundaries and anomalies of the world in the hopes of providing a new escape from the Underground. His research led him to the study of SOULs, and he worked tirelessly to understand the intricacies and differences of both monsters and humans. At times, he called upon the human child of the King and Queen, who seemed more than willing to participate in the simple, yet vital tests that Gaster had fashioned to test his theories. Eventually, his work led him to create a portal in a hidden space within the CORE, one that proved too unstable to use. Before he could announce its creation–or subsequently gain the approval to tinker with it further–an accident occured. If one could call that kind of shove an “accident”.
Caught between his own world and the void, Gaster was given the self-awareness possessed by any out-code character, though without the means to return to his own timeline. All he could do was watch the denizens of his Underground carry on with their lives, slowly forgetting his existence–save for his two abandoned sons. With no way to contact them, Gaster settled into his limbo and began to take Undertale apart, one string of code at a time. It is then that Frisk, and by extension a Player, entered the confines of the system. In mounting horror, Gaster watched as the pair saved monsterkind, only to return and toy with the outcomes, over and over, searching for any number of odd, sad, and ghastly paths. At last, with seemingly no other stone left unturned, the entities began a Genocide run.
Despite his efforts to halt the Player in their tracks, Gaster found himself unable to steer them off-course. It is only in his panic that he discovered a new string of values–FUN values, buried in the data. As Frisk was driven to the end of the run, the Player hesitated, stalling just before they could enter the church. With no time to ponder the consequences, Gaster mounted a RESET of his own–a total re-roll of events through a change in crucial code. Through the upheaval, the world is rewritten anew, birthing the AU known as Undertop.
Gaster is reunited with his kind, though not without consequences. With his return, Asgore’s death remains permanent, as only one can remain to be the leader of the newly-formed troupe. Abandoned and left waiting for the player’s arrival, Chara remains trapped in a limbo of their own, caught between the AU and an expanse of nothingness, seething as their chance to end it all goes awry. Only Gaster and Sans remember the past timelines, with the latter holding little but contempt for the father that abandoned him for the sake of his work. The animosity builds as they both realize there is no turning back–this new story is what remains of the lives they once had.
As ringleader, Gaster discovers a talent for acting, filled with enough pride and charisma to perfectly execute any number of performances. Renewed by his second chance at life, he takes great joy in amazing others, just as he used to during his time as royal scientist. However, despite the smooth transition, he finds his new accomplishments menial in comparison, leading him to continue his research on the reconstructed world, as well as on the existence of other out-codes. All the while, he feigns ignorance, pretending to be an in-code character to avoid attracting the interest of those who could harm his new AU. Not long after, he meets Ink!Sans, a strange being who shares his views, however cynical and nihilistic they appear to be at first glance. He becomes attached to the newcomer beyond the scope of his studies, connecting to him in a way only two outsiders can. As they grow closer and begin to play off of one another more, Gaster officially takes Ink!Sans under his wing, desperately missing the connection he’d long lost with his own Sans. All the while he continues to slowly repair the relationship with his biological sons, even as it remains stilted.
As a proud and stubborn monster, Gaster seeks to mend his ways, all while looking to curb his once rampant superiority complex. He strives to put his knowledge to use for the betterment of the new world, looking to atone for his inability to ACT sooner in past RESETs. Gaster treats his circus members like family, and maintains a very strong fondness for children, both human and monster alike. He does not hold Frisk responsible for the actions of the Player that manipulated them, and welcomes them into the fold. Though Chara remains a looming threat to the peaceful existence within the circus, Gaster is determined to throw them out of Undertop for good, or to otherwise satisfy their cravings for destruction elsewhere. As ringleader, and subsequent chief of the circus, he aims to set a good example to all that fall in his care, and to put on only the most dazzling, jaw-dropping performances for his audience.
In meeting Aster, Gaster gains a new perspective on the multiverse at large, as well as his own life. He is immediately fascinated by their many differences and similarities, and grows fond of him in their time together. Aster inspires him to appreciate even the small things in his life, and renews his love of scientific research. He admires his other half for how well he carries himself despite his hardships, and in turn recognizes that their difficult pasts need not define what they do as they move into an intertwined future.
[Alt. Ref 1] [Alt. Ref 2] [Alt Ref 3]
Zephyrtale Gaster (Aster) grew up taking on the role of parent for his two little brothers, Sans and Papyrus, in a world where humans had long chased monsters away into mountains on the opposite side of the world. Gaster Blasters are a species of skeleton dragons that monsters have learned to study, tame and mount. A good part of the monster economy, transportation and army begins to revolve around the practice. As the young and ambitious royal scientist of the Kingdom, Aster struggles to handle his responsibility as caretaker, especially with Sans’s declining health over time. During his research, he stumbles upon old remnants of ancient DNA from a Phoenix blaster named Chara, possessing assets that could greatly improve the speed of the kingdom’s medical research. Receiving little support to carry out this initiative due to fear of side effects and fearing for Sans’s life as his condition worsens, Aster begins to test the DNA onto numerous posthumous subjects, then himself so as to swiftly provide a sample to stabilize Sans’s condition. The DNA finds the perfect vessel in him and takes over, resulting in Aster’s own skeleton DNA melding with it. He is found half-transformed into a blaster and in critical condition, and has his title of scientist promptly revoked even after Asgore, King and a good friend, attempts to hide evidence to no avail. Aster is judged guilty for his lack of responsibility and safety unbefitting of a Royal scientist and is sentenced to exile, leaving his two brothers under the care of his childhood friend Grillby, who becomes their caretaker.
Now a pariah with fragile health, Aster lives with a soul corrupted by the DNA of a long gone Phoenix blaster who has just enough power to keep its new vessel alive. He manages to survive in the uninhabited mountains for some time before accidentally coming across a gigantic, wounded and aggressive blaster who doesn’t let him approach. The two flee from one another and meet multiple times over the course of weeks. Aster eventually witnesses its death as it turns to dust, then births back from its own ashes, confirming it to be a Phoenix type. Aster can now understand the blaster through telepathy as he has piqued the blaster’s interest, due to the familiar power of his corrupted soul. The blaster introduces himself as Betelgeuse, and the two decide to stick together.
After months of travel, Aster comes across a tower hidden away in a dangerous area with a high concentration of wild blasters, and finds in that place old remnants of astronomy machinery and tools that spark in him a true passion for the sky and its stars. Given the many twists of his life linked to Phoenix blasters and Betelgeuse’s explanation on the connection between the blaster souls and the stars, Aster begins a decades-long journey of studying blasters and the night sky. He naturally develops a sedentary life there, and takes on the role of caretaker for the blasters that live in the tower with him.
As opposed to his bolder youth, Aster is now a soft-spoken and discreet man who does not enjoy having the spotlight on him due to his lack of interactions with others for many years, as well as his inability to feel legitimate in socializing. He is naturally methodical and down-to-earth due to his scientific qualities, but he also possesses enthusiasm and sensitivity for the world he lives in. Albeit more awkward than he used to be with so few interactions, he remains considerate, patient, passionate and entertaining if given enough trust and time. Aster struggles with guilt, and reminiscing on what he has left behind is a difficult topic he chooses to remain pragmatic about: He believes his punishment was justified and hopes for the best for his loved ones as he devotes himself fully to his life-long work to make his mistake worth it, albeit to a fault.
Gaster helps Aster develop his own sense of self, separated from his self-imposed duty, while also partaking in very interesting, fulfilling conversations on the complexities and burdens of their work as prior scientists, which help him reflect on the priorities of his life. Gaster is also an example of confidence and courage that Aster immensely looks up to and inspires himself from. More intimately, he is very touched by his kindness and well-meaning attitude towards him, and finds true comfort and support by his side.
Years ago, a Gaster pile went around online, organized by @stylincheetah, the creator of @under-top. One user, @comyet, added their own Gaster iteration to the pile, Zephyrtale!Gaster, which caught @stylincheetah’s eye. This Gaster pile served as the spark that started their friendship.
However, as this was happening, the codes of certain AUs merged due to this impromptu collaboration, and the incode character Zephyrtale!Gaster–Aster for short–is transported into another AU from the pile called Undertop. Undertop!Gaster, an outcode character playing pretend as an incode, senses an anomaly in his world and goes out to test the waters with this newcomer. After many long discussions, Gaster comes to realize that Aster himself does not pose a threat to him or his loved ones. Despite that, though, the other’s soul is a concern, as any version of Chara is unwelcome. Aster and Gaster still manage to share a lot of their experiences and similarities, leading Gaster to trust him enough to explain the concept of Multiverse and outcodes to his new acquaintance. Gaster chooses to allow Aster to discover his world, meet its inhabitants, and participate in their lives.
After some time, the Chara from Undertop, supposedly long gone, finds in Aster’s corrupted soul the perfect new vessel. Chara attempts to wrest control over it, endangering not only Aster but also Undertop itself. The anomaly is finally detected by Ink!Sans, who brings Aster back to his AU in haste. Having parted with Aster on difficult terms, Gaster uses his knowledge and powers to momentarily enter Zephyrtale and seek the other out. He is led to his tower by Betelgeuse, who has been caught up on the whole ordeal. When Gaster is reunited with Aster, the two of them have a long conversation where Aster confides further about his past, and the complicated feelings it stirs in him. Gaster does the same. Aster chooses to return the favor and introduces Gaster to his research, his observatory and his lifestyle. The two grow so close that feelings stronger than friendship start to bloom between them. During this time, they eventually confess and decide that Gaster should regularly visit his other half in Zephyrtale.
In keeping up this routine for quite some time, Gaster winds up visiting his partner’s AU while one of its possible endings begins to play out. He finds Aster in critical condition. As Gaster disturbs the scripted events, Aster unexpectedly passes away. Ink!Sans brings Gaster to his Doodle Sphere to try and reason with him, but he is inconsolable. He spends the few following days mourning before Ink!Sans invites him to the Doodle Sphere again, this time to introduce him to a new AU that had just been created by his and Aster’s original creators, who assign Gaster as its official creator and moderator. Entering this AU called Zephyrtop, Gaster reunites with Aster, whose code has been brought over to this new AU. After an emotional reunion, Aster and Gaster agree to leave their cycle of timelines behind to continue without them, and live in an AU they could moderate and write together, which in Ink’s words, is a parting gift from their remorseful creators.
Gaster goes on to explain the situation to his troupe, and the majority decide to continue their lives in this new AU, one free of Chara’s interventions. Ink, per Aster’s request, manages to copy and import his tower, blasters, and sky to continue his research out of passion. The group is left with many problems to solve, but one stands out: Aster, having been freed from Chara’s DNA due to Zephyrtale’s ending, is left to reconstruct his soul without the support of Chara’s strength, rendering him incapable of leaving Zephyrtop. Following years of recuperation and fragile health, Aster at last confirms that his soul has healed, and is now glowing white. Gaster finds it to be the perfect opportunity to propose to Aster. They get married on March 5, 2016, during a beautiful day of spring. The two exchange both rings and souls as is the Zephyrtale tradition. To this day, they remain the creators of their AU that exists out of time and out of reach, ever grateful for each other’s company, and eager to satisfy their never-ending curiosities.
