Unity is a large interstellar ship that was constructed by humans millions of years ago. It was designed to be an entire self-contained habitat, and is cylindrical (rotating to simulate gravity) and has a large central “hub” that is a light and power source. At some point, the humans disappeared from Unity, and much later, several sapient species evolved from the many species the humans left behind.
One of the sapient species, the Kayohash, has a sense of electroreception, which can be used to “listen” to Zero, the artificial intelligence which currently runs Unity, although they must go through a process of “priming” first.
Some Kayohash also reproduce via parthenogenesis (meaning the mother is also the father). One particularly large and influential Kayohash family is comprised mostly of parthenogenetic descendants of one Hira Melrose, whose daughter Juni was pivotal in bringing about some major changes. They are all basically sisters, and “Melrose” has come to refer to a race as much as a family.
Sometime in the distant future, humanity left Earth by means of massive interstellar space-arcs. They were cylindrical in design and used centripetal force as an approximation of gravity, and used a stellar fragment as a combination propulsion/light/power source. These ships and their stellar drive were named “Icarus.”
In one particular ship, with designation 184-31A, humanity had disappeared, presumably due to disease, mutation/evolution, or simply deciding they had colonized enough planets. Whatever the case, they left the internal ecosystem to develop and flourish on its own.
Eventually, several of the animal species had developed sapience, and on one of the continents near the aft of the ship (i.e. the “South”), the sapient species began to congregate and learn what they could about their environment. Having never lived on a planet, they had no reason to believe that this situation was anything unnatural; as far as they knew, the ship simply cared for itself and life was what it was (and even the concept of gravity was unknown to them). They referred to their world as “Unity,” after the mathematical concept.
One species, the Kayohash (distant descendants of a family of genetically-modified platypuses), eventually discovered a large information repository in their home territory mid-ship. A latent mechanism built-in, based on the platypus' electroreception, caused some of the Kayohash to “awaken” to the repository, which filled them with seemingly strange thoughts about the past. Most of these were considered insane. The repository was sent to the scientific/academic government in the South for further study.
Through various circumstances, Juni Melrose, a Kayohash physicist working in the South, ended up assisting a pair of linguists who were trying to learn to translate the information repository. Juni ended up awakening to the repository as well, but having a significant background in science, understood the repository’s information well enough to know what to do with it, but not well enough to come across as anything other than insane. This eventually led to its neural patterns being scanned and its own memories being suppressed.
Eventually, a computational simulation of Juni’s scanned neural patterns (created to try to figure out what had happened to begin with) ended up copying itself into Icarus' various systems, and spread like a virus out of self-preservation. The resulting ship-wide consciousness referred to itself as “Zero,” and ushered in a new era whereby Kayohash would be quite important to the future of Unity, as only they had the electroreception sense necessary to perceive Zero’s communications in any effective capacity. These awakened Kayohash would eventually come to be known as “Oracles,” with the awakening process referred to as “priming.”
Meanwhile, Juni had been the parthenogenetic offspring of Hira, a doctor/shaman, but had decided (for fairly complex and mostly-unexplained reasons) to neuter itself. Eventually, Hira had another parthenogenetic daughter, Thena, who Juni adopted as its own. Thena inherited Hira’s tendency towards parthenogenesis, and it didn’t take long for the Melrose family to become established as a race of Kayohash all their own. Given Zero’s own genesis, it couldn’t help but take a specific interest in the ongoing Melrose family legacy.