Three methods of colonization are used in this setting:
- Teleportation, known as matter transmission or mattermission, the most expensive method.
- Freezer ships, wherein colonists are cryogenically frozen for the duration of the voyage (but roughly half the colonists traveling this way are lost due to mechanical failures).
- Lifeships, the most common method, which are slower but safer multigenerational vessels which may take generations to reach their destination. Unfortunately, as lifeships plod through space, their inhabitants lose technical sophistication. Partly because of this, all spheres tend to suffer spherical regression, that is, the further from the center a colony world is, the less technology its inhabitants use.
A central plot mechanism of the Cluster novels is Kirlian transfer, by which the mind and personality of individuals with a high Kirlian aura can be projected to inhabit a distant body. This is a refinement of mattermission technology, but because only the aura is sent it is far less expensive.
Much of the plot of the series concerns attempts by the Andromeda galaxy, using agents placed through Kirlian transfer, to siphon off the energy of the Milky Way galaxy, which will result in the eventual disintegration of the entire galaxy.
Novels in the Cluster series:
- Cluster (known as Vicinity Cluster in the UK) - 1977
- Chaining the Lady - 1978
- Kirlian Quest - 1978
- Thousandstar - 1980
- Viscous Circle - 1982
Anthony's novel Tarot also takes place in the same universe but is otherwise unrelated to the others.
Tropes in this series:
- Absurdly Dedicated Worker: During Chaining the Lady two-thirds of the Etamin fleet are taken over by Andromedans possessing their key officers, who then start a fight with the rest of the fleet. None of the crewmen on the hostage ships seem to question their orders to suddenly start attacking other ships of their fleet without explanation, and a massive space battle results.
- Bizarre Alien Biology: The series has numerous biologically bizarre aliens, including a water-squirting ball that lives off atmospheric gasses, magnetically-levitating disks of metallic particles that communicate by laser, a teardrop-shaped being with a single tentacle who rolls on a track-ball instead of legs (said ball also serving as the egg for females) and tastes the ground as it rolls, and sentient slime-fish with three sexes.
- Bizarre Alien Locomotion: One of the alien races rolls around on a single large sphere embedded at the bottom of their tear-shaped bodies.
- Bizarre Alien Reproduction: Every species has a different, exotic way of breeding, and of course the hero, as he Body Surfs between the species, experiences them all. Perhaps the best example not covered by another trope is the Spicans: they have three sexes, and whenever all three are present in the same area, mating will occur- not might, will. There are three roles that can each be assumed by any of the three sexes, and the gender of the offspring is determined by which sex takes which role.
- Bizarre Alien Sexes:
- The Spicans have three sexes - impact, undulant, and sibilant - of which all three are required for reproduction. Which sex becomes a mother depends entirely on the order in which they meet.
- The Mintakans change gender with each mating, going from female to male and back again, losing a foot each time.
- Deus Sex Machina: In Chaining the Lady and Kirlian Quest, it turns out that the only way to open an Ancient site is to have two high-Kirlian entities mate near it.
- Dude, She's Like in a Coma: In Chaining the Lady Melody's empty original body is effectively raped by another Mintakan, while she watches from a £ host.
- Easily Forgiven: High Kirlian auras seem to be strongly attracted to each other, and often the protagonist is willing to forgive a great deal of dodgy behavior.
- In Cluster, the female slash agent has tried to kill Flint multiple times, and murdered many other sentients in the process. Flint marries her and they raise a family.
- In Chaining the Lady, Melody fully forgives Llume for her part in the plot to conquer and then disintegrate the Milky Way galaxy, during which hundreds of military men are killed in a fleet battle.
- Fantastic Measurement System: Kirlian auras can be precisely measured with an aura reader. A typical person has a Kirlian rating of 1, while the protagonists are over 200.
- Green-Skinned Space Babe: The humans of Outworld are all green skinned, so these crop up a few times:
- Flint's girlfriend Honeybloom from Cluster is the first in the series.
- Yael of Dragon, Melody's host in Chaining the Lady is green-skinned, and certainly attractive.
- Psyche in Kirlian Quest is a blue-skinned space babe.
- Grey-and-Gray Morality: In Cluster Flint eventually decides that neither galaxy should have the Ancient technology he discovered, because both are willing to act immorally if it ensures their survival.
- Humans Through Alien Eyes: Viscous Circle involves a grotesque and disturbing description of an alien that one of the flying magnetic disk aliens sees; it's very easy not to realize that this is a description of a human being. The rest of the Cluster series often deals with "outsider" views of humanity, sometimes literally through human eyes as body-sharing technology is a major plot device.
- Intimate Healing: In Kirlian Quest, in order to get Herald's injured alien host body healthy enough to get moving again, Sixteen suggests mating, as it's the only way to tap an internal energy reserve in the jet species. It works.
- Lethal Harmless Powers: In Viscous Circle, the Bands stage a mock fight for training in which they inadvertently kill (or possibly drive to suicide) those on the other side of the mock fight by using the light that transmits their emotions between individuals to transmit powerful HATE messages to the Bands on the other side. Afterward, they go through a Heroic BSoD and suicide themselves. It's pretty sad, really.
- Mental Space Travel: Kirlian transfer.
- Painting the Fourth Wall: At one point in Kirlian Quest, Herald realizes that he's speaking in quotation marks instead of slashes.
- Precursors: The Ancients came long before any of the species in the series, and had far greater technology.
- Protagonist-Centered Morality: On Spica Flint accidentally rapes two Spicans because he didn't understand that whenever the three sexes meet they must mate. Then he purposefully rapes two other Spicans (of the same gender) to prevent his capture for the first rape. Then he rapes two more Spicans to nullify an Andromedan agent who has transferred to one of them. When the local authorities finally catch up to him he tells them that their laws don't apply to him because he is a transfer from another sphere. They agree.
- Spot the Imposter: With Body Surfing being a primary plot device, this turns up often:
- In Cluster Flint and representatives of other spheres determine one of them must be an Andromedan agent and try various schemes to spot which of them it is.
- In Chaining the Lady Melody uses tarot cards essentially like an Inkblot Test to spot Andromedan agents.
- Starfish Alien: The series includes a large number of alien races, many of which are this.
- Tactical Rock–Paper–Scissors: Thousandstar has three sapient species compete for control of precursor technology: the spherical HydrO, whose needle-like water jets can penetrate the flesh of an Erb, but are vulnerable to the claws of a Squam; the snake-like Squam, whose claws can cut the flesh of a HydrO, but are vulnerable to the drilling action of an Erb; and the plant-like Erb, whose drilling action can penetrate the carapace of a squam, but are vulnerable to the water jets of a HydrO.
- Tarot Motifs: All over the place throughout the series:
- In Cluster Flint discovers that there is a "church of tarot" that believes all faiths are true and provides readings to any who wish.
- In Chaining the Lady the space ships of the Etamin segment fleet are all named after tarot cards and all even shaped like a tarot suit. The Solarian flagship Ace of Swords for example looks like a giant sword.
- The tarot decks used in the series are a futuristic set with 100 cards and the energy/aura suit alongside the traditional swords, cups, wands/rods and disks/coins.
- Translation Punctuation: Human speech is represented with ordinary quotation marks, and each type of alien speech uses a different punctuation symbol as a quotation mark. By the end of the series pretty much every symbol on the keyboard has been pressed into service.
- Verbal Weakness: Because of his discovery, through most of Kirlian Quest, the astronomer Hweeh cannot hear the word "amoeba" without going into shock.
- Weeding Out Imperfections: The Local Cluster of galaxies and their native sapient species face invasion by an immensely powerful fleet from somewhere else. The invaders are seeking to make the Cluster's star systems suitable for the development of what they call "soul sapience", and part of doing so is to exterminate any "weed-species" that shows intelligence but doesn't show "soul sapience."
