2B/6O

2B/6O is the non-binary ship between 2B and 6O from the NieR fandom.

Canon
2B and 6O are both androids who work for YoRHa. While 2B is a combat model, 6O is her operator. It is immediately apparent that they are opposites in personality. While 2B is stoic and focused on completing her missions at all times, 6O is much more expressive with her emotions. During 6O's first in-game contact with 2B, she asks what the weather is like on Earth. When 2B says that her question isn't relevant to their mission, 6O laughs and teases 2B for her characteristic stoicism. However, it is also clear that 2B cares about 6O, even if she is reluctant to show it. When 6O contacts 2B and tells her about being rejected by another operator whom she liked, 2B does what she can to comfort her, although she claims she is definitely not the person to talk to about it.

6O shows great interest in learning more about Earth, although she can't freely visit Earth as 2B can because she’s an operator unit. She seems particularly interested in flowers, and tells 2B about a type of flower on Earth called the Lunar Tear, which she'd learned about after looking through the bunker's records. 6O says, "I bet you'd look really nice if you put one of those in your hair, 2B. It'd suit your stylish looks!" Ever the pragmatist, 2B replies that she doesn't need it, but decides to send 6O a desert rose as a souvenir from Earth. After 2B finds a rose and sends a picture of it to the Bunker, 6O contacts 2B to thank her, remarking that there must be a some gift of nature that 6O has never seen before. 2B replies that there are - lilies, cherry blossoms, daffodils, and lunar tears, among other flowers. She tells 6O that she'll send more in the future if she can.

Later, when 2B and 9S try to escape the bunker after it has been overtaken by a virus, 6O is also lost to the virus. As they escape, 6O's voice comes over the intercom, thanking 2B for the flowers she'd given her and saying that the desert roses were beautiful. Her voice is distorted and the rest of her words are unintelligible. 2B is visibly disturbed by this. It’s open to interpretation whether the announcement was a reminder to 6O from the Desert Rose sidequest, or if it was her final thank you to 2B, though many believe the latter.

Fanon
2B/6O is quite popular within the NieR fandom. It is probably the second-most popular pairing in NieR: Automata, coming after the somewhat controversial ship, 2B/9S. Fans of this pairing find the relationship between 2B and 6O sweet and endearing, due to the "opposites attract" trope exhibited by the two characters. Some believe that 6O brings a sense of balance and levity to 2B, who is often so serious. The fact that they are a combat model/operator pair ensures that they already have a strong bond. Other fans simply see them as friends, or prefer to ship 6O with the Commander — a pairing that has been the subject of some in-game ship teasing.

As mentioned above, the main rival to this ship is the semi-canon ship, 2B/9S. This ship is preferred to the latter by fans who believe that 2B and 9S have an unhealthy relationship, due to the hidden nature of 2B's dealings with 9S. In a fandom with a predominantly female cast, femslash pairings are also particularly popular, which may be another reason why some prefer this pairing.

2B/6O is the second-most written pairing for NieR: Automata on AO3. It is the second-most written ship for 2B, and the most written ship for 6O.

Fandom
FAN FICTION

Trivia

 * The operator who rejected 6O was also female, which means that 6O is interested in female androids. ("Oh, there's this operator I kind of liked, but when I asked her out, she turned me down.") This lends some credibility to the idea of shipping 6O with another female character. However, it is unknown whether 2B is also interested in women — although the concept of sexual identity is somewhat ambiguous in Automata.
 * Operator 6O is known to send 2B mail via the YoRHa server that is unrelated to her work; for example, she sends 2B messages about her astrology readings.