Conjoiners or the Conjoined (pejoratively referred to by outsiders as spiders) are a human faction dedicated to the advancement of the human mind through artificial augmentation and the direct transfer of thoughts and experiences between individual minds.
Early experiments by the Conjoiner matriarch Galiana and her group on Mars in the early 22nd century involving artificial neural augmentation prompted her to begin experimenting with allowing her subject's implants to communicate — triggering the event known as the Transenlightenment, and the beginnings of the Mother Nest and of the Conjoiners. After losing a war with the remainder of humanity, the first Conjoiners later escaped the Solar System with the help of Nevil Clavain and colonized other star systems. They then progressed to a technological level considerably ahead of the rest of humanity, although still far behind many alien cultures in nearby space. The Conjoiners functioned as a single society for centuries, before the events of Redemption Ark result in them splintering into numerous factions and disappearing from the affairs of baseline humanity by the time of Absolution Gap, by which point they are engaged in the war with the Inhibitors. With the "Rise of the Greenfly", other human factions are wiped out, leaving an isolated enclave of Conjoiners as the last humans in the galaxy, along with the Ultranaut Irravel Veda. Even they are forced to flee eventually, as the Greenflies' grip on the galaxy increases.
Society and Technology
Conjoiners use technology to create a localised group mind. Individual identities are retained, but the group generally functions as a single unit working harmoniously toward its goals. All Conjoiners possess, at the minimum, a net of nanomachines inside their head that mimic their host's brain structure and thus augment the host's neural capabilities. Artificial enhancements such as vision overlays are not uncommon, and Conjoiners can communicate neurally through fields generated by their implants, which may or may not be amplified by background systems depending on the situation. Most Conjoiners use only neural communication with other Conjoiners and do not physically speak. Their implants also offer them a host of other abilities, such as the ability to hack into and operate a considerable amount of advanced machinery; they have little trouble overriding most software security protocols save their own, and can reprogram weapons to attack their users. They also typically modify their own bodies (often using muscle fibres based on those of chimpanzees) to make themselves physically stronger. Also, at least by the 26th century, more modern Conjoiners possessed a cranial crest. As well as being aesthetically pleasing, it allows dissipation of the huge amounts of thermal energy their super-charged brains produce.
Conjoiners are typically used to being part of a group mind, and most experience disquiet or worse if cut off from other Conjoiners. The few who are capable of operating by themselves are viewed with ambivalence by the rest of Conjoiner society. Notable individuals with this capability include Clavain, Khouri, Skade, and Remontoire. Clavain and Khouri joined at older ages than normal, and Clavain would have had early generation implants (though not uniquely so); Skade was trained in isolated operation, and later was supported by the alien construct known as The Mademoiselle.
Although Conjoiners seem monolithic and even like a hive mind to outsiders, they each possess their own varied and distinct personalities and deep divisions of thought and opinion still persist amongst them. Clavain later tells other characters that each Conjoiner is in fact different and has a different mind as all humans do; normal humans simply cannot see it.
Thanks to the enhanced mental abilities provided by their implants, the Conjoiners have collectively achieved technological advances rivaling those of any other human faction in the galaxy. The most well-known of these, the Conjoiner drive, is their sole export to other societies, and serve as the primary propulsion for the lighthuggers used by Ultranauts. Other inventions of note include the cryo-arithmetic engine, hypometric weaponry, the Exordium device, and the infamous hell-class weapons.
Conjoiners in the Revelation Space series
Major and named Conjoiner characters appearing in the series, sorted by works they appear in.
- The Great Wall of Mars (short story)
- Redemption Ark (novel)
- Absolution Gap (novel)
RS Glossary entry
Conjoiners: A human faction employing extensive mind-to-mind linkage. Emerging from Mars at the time of the Transenlightenment, Conjoiner technology made human starflight practicable.
- description from the official RS glossary 
In the afterword of Galactic North, Alastair Reynolds comments that the Conjoiners are not an entirely new concept, and may owe some of their origin to the Human Hive-mind culture from Michael Swanwick's Vacuum Flowers.
- Revelation Space universe - RS Glossary - C, AlastairReynolds.com, the official website of Alastair Reynolds
|General overview: Timeline|
|Historical eras: Amerikano era | Belle Epoque|
|Major: Demarchists | Conjoiners | Ultranauts | Skyjacks|
|Minor and local: Banshees | Coalition for Neural Purity | Inundationists|
|GROUPS AND SUBCULTURES|
|Gillies | Hermetics | Mixmasters|
|Norte | Canasian | Russish | Castellano|
|Social and political: Ice Mendicants | Inundationists | Vahishta Foundation|
|Law enforcement: Constabulary | Panoply|
|Research institutions: Mixmasters | Sylveste Institute|
|Spacecraft crews: Captain | Gunnery Officer | Pilot | Shipmaster | Triumvir|
|Law enforcement: Constable | Prefect|
|Civilian professions: Mixmaster | Street vendor|
|Dream Fuel | Indoctrination Virus | Ferris marks |
Palanquins | Polling core | Wedding gun
|Brezgatnik | Hermetic | Shadowplay | Transenlightenment|
* - note 1
** - note 2