The next car is probably a fart car, where everything is just a fart.
|—Sad-One and Glad-One bickering over what the next car will be at the pilot.|
One-One is a robotic companion of Tulip who is trying to help her find a way back home. One-One can split into two halves, each with its own personality. The two halves are called Sad-One and Glad-One by the production staff, but as a single unit, they are called One-One. One-One is also the true conductor of the Infinity Train and regains his position at the end of Book One.
One-One is a white, spherical robot with a black stripe that runs down the entire circumference of its body. On the front, the black stripe has two white dots that appear to be Sad-One and Glad-One's eyes when they are fused. One-One has four retractable spider-like legs.
The body can easily separate into two identical and independent parts and can reattach itself together again. Each half is semi-spherical in shape with a black line at their base with a single white dot, their eye. The flat base of each half has four spider-like legs, similar in structure to when it was whole.
PersonalityAs One-One is a twin single robot composed of two independent parts, it has two separate personalities. As a single unit, One-One often flickers between the two different personalities.
Sad-One, the sad half of One-One, is morbidly pessimistic, practically always having a monotone voice and acting very downcast no matter the situation. Sad-One is almost always in a state of despondency, often shooting down any hopeful remarks. Though Sad-One is always pessimistic, it will sometimes drop pearls of wisdom that, ironically, encourages people.
Glad-One, the glad half of One-One, is cloyingly optimistic. It has a strong sense of happiness, never speaking in a voice that is not overjoyed. Glad-One never deviates from his happiness and will always see life in the most optimistic way possible. Glad-One is also very naive, to the point of doing things with reckless abandon. Its naiveté, mixed with its strong sense of optimism, makes Glad-One have a strong lack of self-preservation.
At certain times of stress and guilt, Sad-One and Glad-One's personalities can merge into a single 'identity', where both sides would talk at the same time.
Not much is known about One-One other than they are the conductor and was ripped out of the control panel by Amelia after they refused to create a car for her. After having their memories wiped, One-One was planted in the snow car by Amelia, where Tulip first meets them.
One-One is seen by Tulip sitting atop a snowman. One-One questions if Tulip is his "mother", which she denies, but still befriends and takes along the journey home. He and Tulip play around in the Grid Car until a Ghom enters it, Tulip asking One-One to make a wall with a small hole around the door so they can exit the car without the Ghom following. One-One is successful in doing so, and they escape unharmed, beginning the trip to the engine.
One-One is traded to the Cat in exchange for the aforementioned feline asking the Conductor to let her leave. One-One bids an unwilling farewell to Tulip, though Tulip feels immense grief and allies with Randall to chase down the Cat and break the deal. One-One is retrieved again.
One-One accidentally alerts the Steward to their location, though once the Steward realizes that One-One is present, it ceases its attack.
One-One tries to connect to the crystal through song, though his idea of a song is dial-up noises, so it fails. He sings with Tulip to make the Giant place the staircase up.
One-One briefly questions if a globe seen in The Cat's Car is his mother. One-One says "we don't like you." to The Cat before exiting the car.
One-One's conductor instinct kicks in, seeing the sloppy work of Amelia and feeling a large necessity to "fix" the car. He ends up causing a massive hysteria with the citizens. One-One keeps telling himself that "it's [his] fault", likely referring to how he let Amelia take over and create sloppy cars such as this. Tulip makes him snap back to normal, and he apologizes.
One-One distracts the Mirror Police while Tulip convinces Mirror Tulip to help.
One-One has fun playing around until the Steward crashes the party. One-One is told to escape by a captive Tulip, who rolls into a tube, but the Steward opens fire and makes it appear as if One-One is dead. He is revealed to be okay after the Conductor and her subordinates leave, and tries to find a way to help Tulip restore Atticus.
He joins the Cat and Tulip in Amelia's tape. He is able to manipulate the tape to see more than what others would normally see.
One-One finally reunites with the Infinity Train, conducting it once more. He opens a new exit for Tulip and bids a final farewell to her.
The Train Documentaries
As part of an effort to better acclimate new passengers to the train, One-One records various "documentaries" about all the cars.
Mirror Tulip alters her appearance and continues to explore the train briefly watching a new passenger watching One-One's introduction video. After a narrow escape from the Mirror Police, Lake ends up in the Family Tree Car where she meets Alan Dracula and later Jesse.
The Apex, most of whom boarded the train during Amelia's time as the Conductor, all claim that One-One is in fact a usurper and is telling them lies about how to get off the train.
Mirror Tulip, in a bout of frustration after discovering she is unable to get a number, starts destroying the robots and equipment in the Passenger Preparation Car. She is interrupted by the arrival of the repaired Steward, whose head opens up to reveal One-One. Glad-One politely asks her to stop destroying everything, with Sad One adding if she doesn't he will have to start writing her obituary.
One-One refuses Mirror Tulip's demand for a number or an exit door, claiming it is impossible for a denizen to leave the train. He reminds her that denizens are supposed to help passengers and she proved very helpful for Jesse. However, he is surprised to discover despite having a zero Jesse has returned to the train. Upon learning that Jesse's problem that brought him back was to help Mirror Tulip get off the train, One-One gets trapped in a paradox, where he cannot let Mirror Tulip off the train without a number, but he cannot solve Jesse's problem without letting her off the train. His distraction starts to damage the train, and in his confusion he hesitantly gives Agent Sieve permission to destroy Mirror Tulip. Finally, Mirror Tulip manages to convince One-One she has a number by reflecting Jesse's number off her hand. Satisfied, One-One opens a door that will allow both her and Jesse to exit. He witnesses Alan Dracula saving Mirror Tulip's life by destroying Agent Sieve, and Alan Dracula's sudden exit from the car back to his own. One-One comments that he really broke the mold with the deer.
- One-One's two personalities share similar traits with Wheatley from Portal and Marvin from The Hitchhiker's Guide to the Galaxy.
- According to Tulip, One-One has been on the Infinity Train its whole life.
- Sad-One is left-handed. This has correlation with many popular medieval beliefs that the left hand is the hand of deviance, sadness, and destruction. The right hand is seen as being the hand of happiness and prosperity, (hence the positivity with the word, "right," in the English language).
- One-One makes an appearance in the background of one of the shorts in Cartoon Network's miniseries Villainous.
- One-One's design was inspired by Star Wars, and other sci-fi robots.
- One-One is one of many heroes that got turned to stone in "Crossover Nexus", a crossover episode in the show "O.K. KO" that uses most of Cartoon Network's shows.
- Another reference to One-One being the true conductor of the train is shown in the actual logo of the show, as the infinity symbol is actually the two halves of One-One.
- One-One has the most appearances in the show.
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