~One (TPOT) ~

One is nonchalant, calm and seemingly helpful, but is very manipulative and malicious under the surface. She seems to constantly observe the contestants and knows their vulnerabilities very well, which she exploits to convince (or blackmail) them into signing her deals, often for rewards she may or may not actually give.

One is easily irritable and gets annoyed when people are hesitant or resistant to her and gets enraged when people defy her, like Donut and Leafy do in "Last One Standing". The episode shows One to be incredibly cruel and manipulative, showing no remorse for the destruction and deletion of contestants that she is responsible for, as well as convincing Pencil to give her all of Two's and Four's power. She is also very power-hungry, conspiring to take Two (and later Four's) power and gleefully fidgeting with it when she finally gets it in "Last One Standing".

In the past, prior to her isolation, One appears to be a nice but lonely person, eager to make friends with the other Algebraliens, eventually befriending Three. However, she also acts impulsively and doesn't realize what she's doing until it's too late, killing Three for betraying her before desperately trying to fix it. She tries hard to patch things up that she did wrong, in fear of not being accepted and remaining alone. After being locked up inside the Moon, her desire for revenge against the others (especially Four) grew, although she still showed remorse for her actions.

Even in the present day, she still is hurt by her loneliness, evident when she forcefully kicked Leafy out of her dimension after her constant remarks of One being alone and sad, meaning she still holds some amount of insecurity despite her antagonistic behavior. Overall, One is shown to be vengeful and manipulative, but below the surface, regretting and lonely.

One is an Algebralian and most likely the main antagonist on Battle for Dream Island: The Power of Two. She made her first canon appearance in the stinger of "Outbreak At Stake". Prior to that, she first debuted in "X Finds Out His Value" and was shown as a recommended character in "The Tweested Temple". She had her first major role in "What's Up Bell's String?", where she is seen kidnapping characters and making deals with them. It is suspected that Four might've trapped One in the Moon to keep her out of reach from Two Body colors: Cornflower Blue (body)

One is a light blue Arabic numeral 1. One's color is similar to that of Four, except for the fact that their color is paler and she's armless unlike the other algebraliens. She is the only algebralien that don't have any arms, hands, anything, Her just have the legs, but she use telepathy to lift up, hold, or interact with something. On some occasions, usually when mischievous or planning something, One’s eyes appear slimmer and more silted.

Stalking, kidnapping, and making a deal/contract with people

Omniscience (debatable): One is somehow capable of recalling the names of Ice Cube and Fanny, even when they haven't met at all previously. Additionally, they were aware of Basketball's presence despite not being able to see or hear her. Though it is debatable that this ability is exclusive to all algebraliens regardless of knowing the contestants. It is also possible that One may have also just learned these names by just spying on them in a conversation when their names were brought up. Super strength and/or telekinesis: In "Outbreak At Stake", she may have kicked a hole through the Moon in the second post-credit scene, or she used telekinesis to break a piece of it off. In "What's Up Bell's String?", she used telekinesis to hold Fanny's new mouth and the list she was holding, having names such as Bell, Bomby, Fanny and Ice Cube with a tick on the left hand side. She probably used telekinesis with her mind. Nigh-Omnipresence: One can be seen being in some of contestant's dreams and hiding in plain sight in certain scenes. The contestant's dreams include: Black Hole, Pen, Winner, Barf Bag, and Book, but One is still in reality. Manifestation/Transformation: When One shows up in TPOT 10, she can sometimes be seen as an object, engraving, outline, or any other inanimate thing. this is because One is in multiple places at once considering the dreams are taking place during the same time. Warping: She's not just able to transform themself. In "Category One", she can also be seen changing the content on the whiteboard without interacting with it directly. Teleportation: One is able to teleport herself and other people as seen in "What's Up Bell's String?". Black Hole Immunity: When One was shuffling the contestants for Team Swap, she moves Black Hole effortlessly without being warped by his gravity. Conjuration: One can create objects out of thin air, as seen when she conjures a document for Fanny to sign in TPOT 12 or creating body parts to offer Ice Cube and Fanny.

From what we have seen, most of the places inside of this dimension seem to have a dark blueish night sky, with stars dotted around the place. The sky shows the design similar to Starry Night by Van Gogh.

One's Room: One's Room appears to be some kind of observatory, overlooking a body of water. It's unknown if they’re actually walls, but the floor is a shiny translucent yellow.

Decorations: On the left side sits a bookcase and a plant, while on the right side is a dead tree, a baby mobile, a floor lamp, and a telescope. Finally, at the centre, there is a siting area that consists of an armchair, a small coffee table, and an office chair.

One's field: One's field is an endless blue plain. It has a road with a field of yellow flowers, and a mini-replica of the solar system in the distance, with the sun seemingly being the area's only light source. In the middle of the road is a red door that leads to the Equation Playground.

Seemingly, One has pocket dimensions, like her room and her field.