The ''Xeelee Sequence'', by Creator/StephenBaxter, is a sprawling series of novels and short stories all set within the same universe.

In the far future, mankind expands out into a hostile universe, filled with intelligent species as [[StarfishAliens weirdly varied]] as they are [[AliensAreBastards ruthless]]. Above them all, however, are the top dogs of the universe: the Xeelee, the god-like de-facto rulers of the universe. The novels of the "sequence" follow various threads, such as Earth being invaded and occupied by bizarre aliens, or a hopeless war between mankind and the Xeelee, along with various other stories concerning humanity's place in a relatively bleak universe.

Overall, the [[InsistentTerminology Sequence]] is a loosely connected series, covering literally ''billions'' of years of history, with later stories expanding the scope to include literally the entire history of the universe, from beginning to end. The main connecting thread throughout all the novels are the Xeelee's enduring presence and influence on the history of the universe and mankind. The series has a definite chronology, but the novels and short stories were published in AnachronicOrder. However, all of them can be read as individual stand-alone stories.

!!!Novels in the ''Xeelee Sequence'':
* ''Raft'': A group of humans are stranded in an alternate universe where the force of gravity is much stronger.
* ''Timelike Infinity'': Set during a time where Earth has been conquered by aliens. A group of cultists TimeTravel 1,500 years into the past but, rather than warning anyone about the invasion, they follow their own inscrutable agenda.
* ''Flux'': Follows a group of highly-modified humans who live inside a neutron star. A particular severe magnetic field instability, worse than any on record, threatens to destroy their home. To survive, a young woman must travel to a far off city, and eventually outside of the star itself.
* ''Ring'': A generation ship is launched on a thousand-year mission, cruising near the speed of light. Five million years pass in the outside world due to time dilation. The ship arrives back in our Solar System only to find that the sun (and every other star in the observable universe) has aged prematurely into a red giant...something that shouldn't happen for another five '''b'''illion years.
* ''Vacuum Diagrams'' (short story collection)
* The ''Destiny's Children'' sub-series
** ''Coalescent'': In contrast to the other novels, this is set on modern-day Earth, with flashbacks to the age of the Roman Empire. George Poole (uncle of Michael Poole, a prominent character in ''Transcendent'') discovers he has a long-lost sister with ties to an ancient conspiracy.
** ''Exultant'': Set during one of mankind's hopeless wars against the Xeelee, this novel follows a young soldier who pulls off an exotic maneuver in battle which results in him time-traveling into the past and encountering his younger self. The bold tactic pays off and they capture a Xeelee ship. But when they return to Earth, he and his younger self are not welcomed as heroes for their breakthrough but rather tried as deserting criminals (true FromACertainPointOfView) and learn about the dark side of their government.
** ''Transcendent'': Follows Michael Poole's early life, as well as a posthuman woman named Alia who's observing Michael's life half a million years in the future. Michael tries to save the near-future Earth's ecosystem from failing, all the while dealing with mysterious visions of his dead wife. A direct sequel to ''Coalescent'', as George and several other characters show up.
** ''Resplendent'' (short story collection)
* ''Xeelee: Endurance'' (short story collection)
* ''Xeelee: Vengeance''
* ''Xeelee: Redemption'' (upcoming short story collection)
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!!This series provides examples of:
* AbsoluteXenophobe: While recovering from the brutal Qax occupation that enforced stagnation and flirted with extinction, humanity adopts an extremely xenophobic imperative that aimed to ensure the future of the species (known as the Druz Doctrines after its founder, Hama Druz). When humanity begins to expand into the galaxy, they become responsible for killing off the entire non-human population of at least one galaxy.
* AbusingTheKardashevScaleForFunAndProfit: The Xeelee have absolute mastery over the entirety of all baryonic matter in universe. Entire galactic clusters are just bricks to these guys.
** Future humans make it to Type III and try to attack the Xeelee by shooting a ''whole neutron star'' at them like a bullet. The Xeelee brush this off as though it were insignificant... because it absolutely was. In the endgame of the war between the Xeelee and the Photino Birds, the Xeelee used hypermassive knots of cosmic string as missile-to-missile defense against ''weaponized galaxies''.
** There's also [[spoiler:the Photino Birds, creatures of dark matter against whom the Xeelee fight a multi-billion year existential war and '''lose''']], who have absolute mastery over all the ''dark matter'' in the universe (which outmasses regular baryonic matter by about 9 to 1), because they ''are'' the dark matter in the universe. [[note]]The ''real'' unbeatable advantage, though, is their mastery of ''time''. They can live [[StableTimeLoop infinitely long]], can temporally duplicate themselves at any time (defying NeverTheSelvesShallMeet), and can travel anywhere, any''when'' instantly. Basically, they pervade the entire timeline of the universe, forwards ''and'' backwards; the only way to beat them is to work ''outside'' of time, and not even the Xeelee can do that.[[/note]]
* AcePilot: Jim Bolder, hence his being entrusted with a [[CoolShip Xeelee nightfighter]] by the Qax, with bad results. [[NiceJobFixingItVillain For]] [[DecapitatedArmy them.]]
* TheAgeless:
** The Qax are practically immortal, since their convection cells can readily be renewed and replaced, without degradation of consciousness. Their human collaborators, the pharaohs, who receive immortality in exchange for service, also qualify.
** The Qax’s tampering with the genomes of the pharaohs (one of whom is the ancestor of most of the ''Mayflower'' crew) [[LongLived imperfectly]] passes on to subsequent generations, so the Autarch ruling class on the ''Mayflower'' choose breeding partners from long-lived families to prolong their own lives, and after many millennia [[spoiler:their subhuman descendants manage to breed immortality into themselves]].
* AgeWithoutYouth: The pharaohs' immortality treatment is imperfect, in that they still age albeit slower than normal humans, as shown by Rusel, the 25000-year-old protagonist of ''Mayflower II'', who spends most of his time sleeping and is barely able to function without his life support systems, and even moreso by the 994721-year-old Luru Parz in ''The Siege of Earth''.
* AliensAreBastards: Played straight with some species. Averted ([[BlueAndOrangeMorality more or less]]) with the Xeelee, who go out of their way to prevent extinction of other sentient lifeforms, even humanity, which repeatedly attacked them.
** Also averted with the Silver Ghosts, who are much less aggressive than [[HumansAreFlawed humanity]] (except the [[DarkIsEvil Black Ghost]]) but unfortunately end up in the path of the Third Expansion.
* AlienSea: On the Core of Cores, there are oceans of some quasi-liquid material, thick and red as blood; they lap at lands that thrust above the general spherical surface.
* AlternateUniverse: ''Vengeance'' and ''Redemption'' are set in a second timeline that changes most of what we know from the rest of the series. Characters and personalities are taking very different paths, especially for people like Michael and Harry Poole. Monopole cannons have been put to use, a weapon that was humanity's best in the Exultant war period. The Squeem and Qax will most likely be unable to enslave humanity: even if they found the humans on Cold Earth or scattered, they already have technology that could win the war.
* AnachronicOrder: The publication order of the stories does not correspond at all to the chronological order in which they happen.
* ArchEnemy: The Xeelee and the photino birds are at irreconcilable odds because each species is fundamentally seeking to threaten the ideal habitat of the other. Seemingly as a unified species, the Xeelee have concerned themselves with defeating the photino birds for almost the entire history of the universe.
* ArtisticLicensePaleontology: In her VR simulation of the Late Permian, Gea uses the term 'mammal-like reptile' to refer to animals that were not, like [[UsefulNotes/PrehistoricLifeNonDinosaurianReptiles pareiasaurs and procolophonids]].
* BaldWomen: Women without hair appear in various degrees of frequency in the stories set during the Qax occupation and later.
* BalkanizeMe: The Interim Coalition of Governance collapses almost immediately after the withdrawal of the Xeelee, leaving behind countless successor statelets. The Unifier's brief empire also suffers the same fate after its founder's assassination.
* BattleTrophy: The human-descended 'drones' in ''In the Un-Black'' have the habit of taking trophies from their kills.
* BeePeople: The Coalescent human hives, including the [[spoiler:Puissant Order of Holy Mary Queen of Virgins]], some of the outlying human colonies isolated during the Qax occupation, and the [[spoiler:Coalition's Archive inside Olympus Mons]]. Males are outnumbered by females, most of whom are sterile and serve the hive as workers, helping their mothers produce more siblings; any female that becomes fertile will spend her entire life producing babies. For example, [[spoiler:in the Order, boys are born, but there are few of them, and they either leave or are gay. Most girls do not reach puberty, remaining prepubescent in their physical appearance; those few that do develop a spermatheca and become veritable baby factories that can churn out hundreds of children from menarche to death. The women develop a way of communicating with each other through body language and pheromones that takes place almost unconsciously]].
* BenevolentPrecursors: The Xeelee are one of the first species to develop and gain sentience after the universe's formation; indeed, their progenitors are older than physics as we know them today. They rarely take direct interest in messing with lesser civilisations, and are usually benevolent in the rare case they do. [[spoiler:Their ultimate goal is to provide a way for all baryonic species to escape the doomed universe and the photino birds via Bolder's Ring]].
* BigDamnVillains: The [[spoiler: Qax]] are tricked into fulfilling this role at the end of ''The Baryonic Lords'', distracting the photino birds long enough for the last of humanity to escape through the Ring.
* BigDumbObject:
** Bolder's Ring, built by the titular aliens; it's constructed out of cosmic strings (and is revealed to be the cause of the RealLife [[http://en.wikipedia.org/wiki/Great_Attractor Great Attractor]]) and is essentially a black hole that has been stretched into a one-dimensional loop millions of light years in length. It's eventually revealed [[spoiler: to be an escape route for the Xeelee from the Universe, by means of tearing a hole in spacetime through the middle of the ring via the unimaginably strong gravitational forces created through its rotation]].
** The Sugar Lump - a perfect cube the size of a small moon, which appears to serve no purpose whatsoever. [[spoiler: Later is revealed to be one of many identical devices which sent the Xeelee back in time to essentially create themselves using a StableTimeLoop]].
** The Snowflake is a regular tetrahedron built around the remains of a black dwarf. It measures over ten million miles along its edges. How it maintains its structure in the gravity well of the star remains unknown. While possessing about the same mass as the Earth, it has been puffed out like candy-floss, filled with struts, threads and whiskers of iron, like delicate scaffolding. It has a fractal architecture with the tetrahedron motif, repeated again and again, on all scales. [[spoiler:It is actually a gigantic computer created by the Snowmen to record anything in the universe up to the quantum level]].
* BirthDeathJuxtaposition:
** In ''Coalescent'', the birth of Brica and the death of the midwife [[IllGirl Cartumandua]] happens within minutes of each other.
** The birth of spacetime-defect creatures is a quantum process. The uncertainty principle dictates that it is impossible to clone quantum information: it could be swapped around, but not copied. For the daughter to be born, the mother’s genotype has to be destroyed. Every birth required a death.
* BiTheWay: Quite a few characters in the stories set in the Third Expansion and latter eras don't really care about the gender of their sexual partners.
* BittersweetEnding: [[spoiler: The Xeelee ultimately [[TheBadGuyWins lose against the Photino Birds]] and the universe becomes unsuitable for baryonic life. However in one last act, the Xeelee give the remnants of humanity and others a vessel to escape to a new universe where they can hopefully build civilization anew.]]
* BizarreAlienBiology:
** Qax biology is based around chemical cycles embedded in convection cells. A Qax is composed of millions of such cells that exist in any kind of turbulent fluid (water, air, gas giant, star, [[spoiler:space-time]]). In short they’re highly organised, living storms.
** The eponymous creatures in ''The Logic-Pool'' are a species of white light-worms who are living logical entities made of mathematical postulates and quantum non-linearity that live for the advancement of more and more complex math.
* BizarreAlienSenses: The modified humans in ''Flux'' 'see' sound waves which are transmitted through the Air (their term for the neutron superfluid in the neutron star), 'smell' photons that can only diffuse slowly in the Air, and 'hear' temperature fluctuations.
* BlessedWithSuck: Sometimes a pharaoh's children are born with Qax immortality. But they don’t all grow - they stop developing, at the age of two years or one year or six months or a month; some of them even stop growing in the womb and have to be aborted.
* TheBlacksmith: [[Myth/KingArthur Myrddin, the genius advisor of Artorius and supposedly a wizard]], is depicted in ''Coalescent'' as an iron-making genius.
* BlobMonster: Swimmer-with-Somethings looks disturbingly like a flayed human, immersed in a kind of gummy soup within which smaller creatures swim.
* BondVillainStupidity:
** When the second [[AliensAreBastards Qax]] governor of Earth takes two Spline warships and travels back in time 1500 years to invade Earth and destroy the human race, it brings alongside Jasoft Parz, the human ambassador to the Qax regime, with the intent of forcing him to watch Earth's destruction. Parz then proceeds to sabotage the warship, foiling the invasion, and even calls out the Qax on this:
--->'''Jasoft Parz:''' And, even worse, you carried me — a human, one of the enemy — in your warship’s most vulnerable place; and for no other reason than to heighten the exquisiteness of your triumph. Complacency, Qax!
** The [[spoiler:Black Ghost's]] undoing comes from arrogantly letting a group of humans enter its lair, believing that their weapons can do nothing against it. It was partially correct in that none of the humans' weapons can penetrate its hide... but [[spoiler:the Black Ghost surely didn't anticipate having said hide opened by the enemy's bare hands and mouth and then getting killed by a bullet that goes through this open wound]].
* CallASmeerpARabbit:
** The term 'photino bird' is one, as these creatures are obviously not birds, or even matter at all.
** To the tiny Starfolk that inhabit the neutron star in which ''Flux'' takes place: 'Air' is the neutron superfluid in which they live; 'plants' and 'animals' are, respectively, the sessile and mobile indigenous lifeforms of the star (the 'plants' are in turn divided into 'trees' and 'grasses'); 'wood' is the building material made from the 'trees'; 'leaves' are the edible appendages of the 'trees'; 'wheat' is the 'grass' cultivated for food ('bread'); 'Air-pigs' are the main 'animals' used as livestock; 'Air-boars' are the savage cousins of the Air-pigs; and there are also 'animals' called 'spin-spiders' and 'rays'.
** The Squeem, the Titan fauna and the lifeforms of Beta are sometimes described as 'fish', 'spiders', 'birds', 'whales', 'trees' or 'lilies', despite being aliens that only physically resemble these animals and plants.
** ''Exultant'' uses terms as 'plant', 'animal', 'fish', 'bird', 'insect' or 'flower' to refer to the various types of lifeforms that inhabited the primordial universe, where atoms didn't even exist yet.
* CallingParentsByTheirName: Michael Poole casually calls his father Harry Poole by his first name. Later in her life Hank Poole starts to do the same thing to her mother, as generation differences are kinda blurred when her own son became a centenarian.
* CapitalOffensive: Both the Starfall invasion of Earth and the Squeem invasion open with an attack on New York City, then-capital of humanity.
* ChildSoldiers: Most of the main characters in ''Exultant''. The Druz Doctrines' primary article of faith is that “a brief life burns brightly”: most of the human soldiers who fight the Xeelee are no older than 16.
* ClothesMakeTheSuperman: In ''Hero'', the amazing powers of the eponymous superhero comes from his suit.
* ColonizedSolarSystem: Humans start to colonise the Solar System during the 3rd millennium.
* ColonyDrop: There's the extreme colony drop option where a Neutron Star is accelerated to high fraction of light speed and smashed into Bolder's Ring (see BigDumbObject above).
* CombatClairvoyance: The Integrality's Adepts have a limited precognitive ability. They could see a few minutes, or less, into the future, and only aspects of it that concerned their own surroundings – their own destiny. That few minutes' edge made them formidable soldiers, enough to let them get out of the way of the next bullet.
* ConLang: InUniverse, as part of their great Extirpation to erase all human culture, the Qax force humans to speak a constructed language.
* TheConqueror: Sixty-five thousand years after the conquest of the Galaxy, the self-styled, charismatic, monstrous Unifier, using one human type as a weapon against another and carelessly spending human life on a vast scale, briefly forges an empire before his assassination leads to its disintegration.
* ContinuityNod:
** Near the end of ''Ring'', Louise and Spinner visit the same neutron star as the setting of ''Flux'', and later, before [[spoiler:the ''Great Northern'' passes through Bolder's Ring, its crew has a brief glimpse at the alternate universe depicted in ''Raft'']].
** ''The Seer and the Silverman'' ends with the independent human colony [[spoiler:pulling out the old Susy drive from ''The Quagma Datum'' for a wild plunge forward]].
* CoolGate: Bolder's Ring is a [[spoiler:portal to other universes, meant to provide an escape for the Xeelee and other baryonic species if the universe was destroyed]].
* CoolShip: Xeelee nightfighters, which can travel at near-lightspeed even before they fire up their hyperdrive, by flapping wings made of folded space-time.
* CrapsackWorld: Millions of years of humanity in a massive HopelessWar of attrition against the Xeelee [[spoiler: who are also fighting a race of dark matter beings who want to render the universe unfit for baryonic life (like humanity)]]. [[spoiler:They lose. First the humans, than the Xeelee.]]
** [[spoiler: Well, at least the Xeelee not only managed to get the hell out of the doomed Universe, but also provided means for at least the remnants of humanity to escape. While some refugees from our Universe ended up in one that was practically unfit for human life, this wasn't any of the known evacuation groups, so there is at least some hope for the humanity...]]
* CreepyGood: [[spoiler:The human hive of Coalescents is basically a group of Roman Christians who unconsciously adopt eusocial reproduction patterns because of the hardships during the end of the Western empire, eventually evolving away from standard ''Homo sapiens''. They grew wealthy during centuries, and use most of that wealth for charity and educating those who would otherwise not recieve any education. Basically, they are really alien and creepy, but benevolent in their conscious goal (the unconscious one is, of course, preserving the hive).]]
* {{Cyborg}}: The Spline genetically engineered themselves to be organic starships, and support themselves by being hired by various alien empires. The employers can mount whatever weapons or equipment they want in each Spline, as long as it doesn't adversely affect the Spline's health.
* DeadGuyJunior: Symat, protagonist of ''The Siege of Earth'', is named after Symat Suvan, an old friend of [[spoiler:his creator]] Luru Parz, who lived nearly a million years before him and appears in ''Cadre Siblings''.
* TheDeadHaveNames: On the nameless Rock that the protagonist of ''Riding the Rock'' visits, the soldiers carve the name of their dead on the surface. And within the grooves of each letter are inscribed more names, and there are many more layers of names nestled within each other.
-->''There were more layers than he could count, more names than could ever read if he stood here for the rest of his life. Just on this one Rock. And perhaps there were similar memorials on all the other bits of battered debris at every human emplacement, all the way around the core of the Galaxy, a great band of death stretching three thousand light years across space and two thousand years deep in time.''
* DeathbedConfession: Just before she dies, Cartumandua reveals to Regina that her father Marcus cheated his wife by sleeping with her and later atoned by castrating himself; he doesn't survive, and his death is one of the factors that forced Regina to move away from her family villa.
* DeathByChildbirth: Morag, Michael Poole's wife, dies giving birth to their second child.
* DecapitatedArmy: The Black Ghost inspires its kind’s last effective stand. After its fall, the Ghosts’ political unity fragments, and effective Ghost resistance to human conquest comes to an end.
* DeityOfHumanOrigin: The Transcendence is a posthuman collective consciousness with billions of humans spread across the galaxy who are attempting to evolve into a form of godhood, in effect leaving their humanity behind.
* DerelictGraveyard: The Reef is a heap of decommissioned automobiles piled up, crushed down on each other, glittering with bits of smashed windscreen and gaudy paintwork, the whole thing laced together by a patina of orange rust.
* {{Determinator}}: Regina is single-minded in her intent to forge ahead and adapt to circumstances, and her instinct for survival often prompts her into heartless and calculating actions; she actually trades her daughter's sexual services to secure passage to Rome from Britain. But it's also this instinct for survival that informs her leadership of the Puissant Order of Holy Mary Queen of Virgins, and her ideas about the preservation of bloodlines that becomes the Order's modus operandi in the subsequent centuries.
* DistantFinale:
** The final chapters of ''Timelike Infinity'' take place five million years in the far future, after [[spoiler:Michael Poole is trapped there due to the destabilisation of the wormhole interface]].
** Most of ''Coalescent'' is set from the waning days of the Western Roman Empire to 2005, except for half of the final part, which takes place during the Third Expansion, in a human colony that has been knocked out of its solar orbit, and whose inhabitants have developed eusociality to adapt to living underground in the scarcity of living space and resources.
** ''Ring'' ends in the ''[[TimeAbyss very]]'' far future [[spoiler: where, while the Photino Birds rule the Universe, all stars have died and proton decay is decomposing their corpses. Michael Poole with NothingLeftToDoButDie kills himself by falling into a neutron star]]
* DoomedHometown:
** In ''Raft'' (which is set in an AlternateDimension), the nebula where the humans live is turning into an increasingly hostile environment and the humans, suffering the effects of environmental collapse, need to migrate to another nebula. In its sequel ''Gravity Dreams'', the alternate universe itself is dying, and the story involves the humans trying to get back to their home dimension.
** In the Photino Victory stories, the humans' PocketDimension is failing and will eventually freeze and become uninhabitable. The theme of ''The Baryonic Lords'' is the humans' search for a way to escape their dying home and seek another.
** [[spoiler:The entire universe is this for the baryonic species: there's no way to prevent the photino birds from making the universe uninhabitable for them. The goal of the Xeelee is to provide a way out of the universe for all baryonic species via Bolder's Ring]].
* DysfunctionalFamily: The relations between the members of the Poole family are a non-stop car wreck.
* DysonSphere: The setting of ''The Lakes of Light'' is a star encased wholly by a sphere made up of Xeelee construction material. During the Xeelee Scourge, the Xeelee take care of the human vermin by encasing their star systems within such spheres.
* {{Egopolis}}: The capital of the tiny humans in ''Flux'', Parz City, is most likely named after Luru Parz.
* ElaborateUndergroundBase: The Order runs a vast subterranean complex, located beneath the Catacombs, the ancient underground Christian tombs on the outskirts of Rome, described by George Poole as nuclear bunker and Vatican crypt rolled into one.
* EldritchAbomination: The Xeelee are creatures made of the raw fabric of the universe twisted into arcane forms that lived and forged long forgotten civilisations in the first billionth of a second of the universe's existence and have watched the passing of aeons. They were here when the primal forces diverged from each other, when the universe shifted from an opaque plasma soup to a transparent world of blackness and stars, when civilisations cried out against the first birth of the atom. It is hinted that Xeelee have combined with their technology (and possibly symbiotes) to such a degree that they have no real 'body'.
* EldritchLocation: ''Raft'' is set an alternate universe where the gravitational force is a "billion" times as strong as our own. Stars are only a mile across and have extremely brief lives, becoming cooled kernels a hundred yards wide with a surface gravity of five g. Humans possess a "respectable" gravity field in and of themselves.
* TheEmpire: The Coalition regime is repressive, controlled, fanatical, extremely xenocidal, and responsible for the staggering slaughter and extinction of virtually all other sentient life in the galaxy. Their ultimate goal is basically the complete genocide of all non-human civilisations ''everywhere''. One of its successor states, the Ideocracy, is explicitly the Coalition 2.0, except they are even more hypocritical and willing to actively manufacture an apparent nonhuman threat.
* EmpireWithADarkSecret: The Silver Ghosts spend a million years denying [[spoiler:the bloody civil war that followed the death of their sun]], and they don't want anyone else to learn about its existence either. But that doesn't compare to the skeletons that the Coalition keeps in its closet.
* EndlessDaytime:
** When the universe was ten million years old, many worlds were warmed by the afterglow of the Big Bang itself, where the sky was still glowing with a comfortable heat. The whole universe was then habitable, where you could potentially find liquid water on any planet surface, no matter how far from a star.
** The home planet of the Silver Ghosts and many others are tidally locked to their sun, meaning that one side experiences perpetual daytime and the other perpetual night time.
** The planets located near the centre of the galaxy (like Base 478 in ''Between Worlds''), where, despite the absence of a sun, never knows night due to the heavy star density near the galactic core.
* EternalEngine: The Coalition dedicates certain planets as factory world to generate the materials and weaponry used by the Green Army and Navy along the Front.
* EvilPoacher: A group called the Last Hunters seek to become the killer of the last individual of each endangered animal species.
* EvilVersusEvil: In the finale of ''The Baryonic Lords'', Paul tricks the [[spoiler: photino birds into thinking the Xeelee are returning, leading them to aggressively ramp up their destruction of the Ring. The genocidal Qax remnants - who have been waiting patiently to exterminate the last humans - have a collective "oh shit" moment and lead a last ditch attack on the birds at the Ring so that they can escape the universe. The humans use the confusion of the battle to sneak through the Ring, escaping both the Qax and the slow death from the machinations of the birds.]]
* FantasticCasteSystem: The society in ''Raft'' is highly stratified, led by the Officers, descended from the officers of the original ship that came through Bolder's Ring, who share the Raft (the remains of the ship that contains almost all the high technology) with the scientists and some of the labourers; the various Belt worlds are inhabited by the majority of miners that mine burnt-out star kernels in bad conditions; and there are the cannibalistic Boneys who live on worlds created out of corpses. People are born into their class, work in it throughout their life and usually die in it. There is talk about being able to rise to the top with talent, but this seems to be predominantly a myth. There is at least one case where this happens (Rees) but it's clearly far from usual.
* FantasticNamingConvention: The nobility of Old Earth write their given name and surname as a single word in a CamelCase style. Only the eldest son and eldest daughter of each couple inherit their father's surname, the others taking the surname of their mother.
* FascistButInefficient: It is shown time and time again that the harsh conditions of the Coalition do not equal a well-run state. It is little more than the ghost of Hama Druz, a shell waiting to collapse, needs endless militarism and expands resources to keep its own control functioning. For related reasons, [[spoiler:the Coalition collapses almost immediately after the Xeelee withdrew from the galaxy]].
* TheFederation:
** In ''The Sun-People'', which is set in AD 3672 during humanity's early expansion, it is directly assumed that the human incursions into the asteroid where the story happens will automatically halt when it comes into conflict with other, and vulnerable, intelligent life. That, combined with the sketched out detail of an array of governments and institutions to be navigated, give a very different feeling from the stories set under the totalitarian, xenophobic, rapacious human regimes in the later eras.
** During the earliest moments of the universe, before the breakup of the GUT force, a multispecies federation established itself among the spacetime-defect creatures of this age.
* FlashStep: The people on the ''Nord'' have the ability to teleport by effort of will, called Skimming.
* FlatCharacter: The story generally doesn't have much interest in its characters, with people being important only insofar as they've connected to current ideologies, current economic realities, or certain modes of scientific inquiry.
* FloatingContinent: The first generations of human colonists on Venus live in cities floating in the Venusian sky.
* TheFogOfAges: Luru Parz claims that the pharaohs can remember events from throughout their lives, but no more or less clearly than a normal person. Sometimes, events may bring forth a distinct memory that hadn't been recalled in several thousand years.
-->'''Luru Parz:''' The scientists used to say that the human brain can accommodate only perhaps a thousand years’ experience. It isn’t as simple as that. Of course we edit our memories, all the time. We construct stories; otherwise we could not survive in a chaotic, merciless universe that cares nothing for ''us''. If I think back to the past, yes, perhaps I can retrieve a fragment of a story I have lived. But I live on, and on, and on, and if I look back now I can’t be sure if I am visiting a memory, or a memory of a memory… Sometimes it seems that everything that went before today was nothing but a dream. But then I will touch the surface of a Conurbation wall, or I will smell a spice that was once popular in Port Sol, and my mind will be flooded with places, faces, voices — not as if it were ''yesterday'', but as if it were ''today''. And do you know what? I ''regret''. I regret what is lost, people and places long vanished. Of course it is absurd. There isn’t room in the universe for them all, if they had lived. And besides I ''chose'' to leave them behind. But I regret even so. Isn’t that foolish?
* ForcedToWatch:
** [[spoiler:After the extermination of a Squeem colony in Lake Superior, the Squeem decide to round out all people who were involved in the act in concentration camps and force them to watch as they freeze all of the water on Earth, killing many humans and causing many species to go extinct.]]
** [[spoiler:The Qax governor of Earth from the future brings along [[TheQuisling Jasoft Parz]] during its invasion of Earth in the past, with the intention of forcing him to watch Earth's destruction. Unfortunately for the Qax, Parz was never loyal to them at the first place.]]
* ForegoneConclusion: In the first part of ''Coalescent'', which is set in Britain after the end of Roman rule, many ex-Roman citizens consider that their hardship is only temporary until the Emperor can sort out his difficulties and reassert his rule over the abandoned province. If you know your history, though, you're going to know that the Western Roman Empire is already on life support in this time, and no Emperor will come to defend Britain from the Saxons who will conquer the southeastern part of the island.
* ForeverWar: The Xeelee are nearly immortal, and humanity quickly proves itself a race of consummate survivors. They don't like each other. Do the math. But even that [[spoiler:pales before the Xeelee-Photino war]].
** Mankind vs. Qax. Infuriated by their improbable repulsion from an enslaved earth, and further goaded by humanity [[spoiler: being indirectly responsible for the destruction of their home system]], the Qax bear their grudge so long that it becomes a ''species imperative'' (i.e. eat, breathe, breed, destroy all humans).
* AFormYouAreComfortableWith: Invoked by Reth Cana when he is trying to find a way for humans to enter configuration space - a realm beyond human experience. Reth constructs metaphors, a kind of interface to make its features accessible to human minds. There is an island — a beach. At the centre is a mountain that represents order, and at its peak is that special dust grain that represents the initial singularity: the Big Bang. The sea is the opposite — maximal entropy — the ocean of meaninglessness to which everything washes, in the end.
* FreudianExcuse: While the Coalition is completely insane, irrational and wasteful, they at least have reasons. Twice occupied by alien powers. Last occupation erased all human history and destroyed Earth's biosphere, placed immortal Quislings to rule humans... And all the species in the galaxy that ventured out of their home systems were more or less that. Opportunistic imperialism and capitalism, any real invention blocked by subconscious inferiority to Xeelee and knowledge that no matter how good you do, the Xeelee have invented it and perfected it before your Sun existed. Sure, some species weren't evil, but trauma on human civilisation was to great to make any decisions about who lives and who dies, so they killed them all.
* FullBoarAction: The 'Air-boars' that inhabit the neutron star in ''Flux'', which are described as savage cousins of the Air-pigs used by the transhuman habitants as livestock. One of them kickstarts the plot of the story by goring Adda, forcing Dura and Farr to seek work in Parz City to pay for Adda's treatment.
* FuturePrimitive: In conditions that do not change and where innovation is not necessary or taboo, humans have a tendency to breed intelligence out of themselves; for example, the [[spoiler:Shipbuilders in ''Between Worlds'' and transients (mortal human crew) on the ''Mayflower'' generation ship are little more than beasts that can nonetheless maintain their ships out of instinct because that's their way of attracting sexual partners]], the Coalescent hive that appears at the end of ''Coalescent'', the fish-like posthumans that briefly appear in ''Transcendent'', the savage 'drones' in ''In the Un-Black'', among others.
* GemstoneAssault: The projectiles (dubbed Probes by humans) launched from the Cache to the human habitats on Earth, the Moon and Mars are diamond rough spheres.
* GenderBlenderName: The protagonist of ''The Venus Generations'' is a woman named Hank Poole.
* GenerationShips: ''Mayflower II'' is set on a generation ship bound for a satellite galaxy 25,000 light years away; at .5c, the trip will take fifty thousand years. A crew of pharaohs rule over the mortal transients. As the ship drifts through space and time, the society of the transients breaks down as the pharaohs slowly die off, evolving into beasts who only maintain the ship out of instinct.
* GeniusBruiser: The tribelike mannerisms of the Boneys from ''Raft'' hide minds well-versed in orbital mechanics to rival trained scientists.
* GenreShift: Unlike every other Xeelee story, ''Coalescent'' is a work of historical fiction instead of a distant-future high-concept space opera; it is set in the past and has little science fiction elements until the end.
* GhostCity: In 2047, declining birth rates in many countries have turned formerly bustling cities into near-ghost towns, as shown by Seville, which is visited by Michael Poole halfway through ''Transcendent''.
* GlobalWarming: Earth in the 2040s is a world drastically diminished. Global warming has raised sea levels drastically and shifted climates around the world, devastating the biosphere and displacing entire nations.
* GodIsEvil: [[spoiler:The ancestors of the Silver Ghosts venerated the pulsar that was destroying their sun, made it a god and called it 'Destroyer']].
* GoneHorriblyWrong: The Friends of Wigner's plan to send a message to the Ultimate Observer involves turning Jupiter into a black hole, shaping the singularity at its heart and loading it with information. The Friends want the Observer to select a chosen history to favour humanity — in particular, to pick out a causal line that would not include the Qax Occupation. Of course their scheme was overcomplicated, and it didn’t work: the Friends didn’t even manage to make their black hole properly, let alone send their plea to the end of time. They managed to destroy Jupiter, though, and in response the Qax begin the Extirpation that wipe clean the history of humanity and Earth itself.
* GroinAttack: In ''Coalescent'', Marcus does this to ''himself'' to atone for his crime of cheating his wife. He doesn't survive long after.
* GrimUpNorth: To the Romano-British in ''Coalescent'', [[UsefulNotes/{{Scotland}} the north]] is an uncivilised land, home to the Pictish barbarians.
* GuileHero / MagnificentBastard: Jim Bolder.
* HeavyWorlder: The human colonists on the Rustball evolved a squat, short body plan with thick, powerful limbs to adapt to their new home's strong gravity.
* HeroAntagonist: Though they are presented as antagonists in the stories set during the Third Expansion era, the Silver Ghosts and the Xeelee don't seek to destroy humanity and only fights the humans because of aggression instigated by the absolutely xenophobic Coalition. [[spoiler:And in the case of the Xeelee, it is revealed that all the time, the Coalition was fighting an enemy that actually wanted to save them, since the Xeelee's ultimate goal was to provide a way for baryonic species to escape from the Photino Birds and the doomed universe.]]
* HigherTechSpecies: The Xeelee are an extreme example. Despite being "only" this trope (because their universe-shattering technology ''is'' recognizable as such), they could absolutely run rings around quite a few examples of SufficientlyAdvancedAliens from other works.
* HistoricalDomainCharacter: Two [[UsefulNotes/TheRomanEmpire Roman emperors]], Romulus Augustus and Constans II, alongside [[UsefulNotes/ThePope Pope Clement VII]], make a brief appearance in ''Coalescent''.
* HistoricalHeroUpgrade: InUniverse. ''The Seer and the Silverman'' refers to Joens Wyman investing in the Susy drive, but after the test case he got bankrupted, suggesting him as an innovative, heroic figure wronged by how things turned out. In fact, from reading ''The Quagma Datum'' (which takes place 199 years before) we know Wyman was a dick, and his financial ruin was a triumphant climax of the story, turning the tables on the callous, amoral fatcat.
* HistoricalVillainUpgrade: Happens in-universe to Jasoft Parz, the human ambassador to the Qax occupation regime. In life, he works to moderate the bleak fact of Qax rule into a livable arrangement for as many humans as possible, and contributes to [[spoiler:thwarting the Qax when they travel back in time to AD 3717 and invade the Solar System]]. After the end of the Occupation, the word 'jasoft' came to be used by the new human regime to refer to traitors who must be purged.
* HiveCasteSystem:
** [[spoiler:The Puissant Order of Holy Mary Queen of Virgins is a hive of eusocial humans who have evolved into distinct castes. Boys in the Order are more or less the same as normal humans, but they are outnumbered by girls and usually leave the Order if not gay. Most girls are sterile, never reach puberty, do all of the Order's work and maintain a childlike physiology well into adulthood; if a girl does undergo puberty, she develops a spermatheca and spends the rest of her life producing three or four children per year non-stop from menarche to death (which is possible since Order matres only need 13 weeks to carry a baby to term and never undergo menopause).]]
** [[spoiler:The Interim Coalition of Governance's Archive, located inside Olympus Mons, is a eusocial hive, home to a vast number of specialised castes: archivists, who have big heads, are much younger and age a lot faster than normal humans; runners, who can run faster and longer but live shorter lives; mechanics, who have long legs to allow them to reach tall places and reach distances faster; drones, normal sterile females that do the menial work; and breeders, perpetually pregnant and always seen floating in some sort of milky liquid]].
* HiveMind: All Squeem are linked into a mass mind. So the death of a single Squeem affected the totality, but only in a minor way, as the loss of a single neurone from a human brain wouldn’t even be noticed.
* HoistByTheirOwnPetard / NiceJobFixingItVillain: Thank you so much for discharging the star-disrupting gun right next to your own sun, [[spoiler: [[WhatAnIdiot Qax]]]]!
* HollywoodTactics: The Interim Coalition of Governance seeks to counter the blatant Xeelee qualitative superiority with numbers and making suicide rushes, billions dying each year for thousands of years to achieve fractional gains. The inefficiencies and stupidity of the Coalition is one of the main points of ''Exultant''. This is a group that thought reviving trench warfare like manual charges would be a good point.
* HomeworldEvacuation: The liberation of Earth from Qax rule was caused when Jim Bolder fires the starbreaker gun at the Qax homeworld's sun, forcing them to abandon Earth and try to save as many individuals as possible before their world burns.
* HopelessWar: Humans stand no chance against the Xeelee, just like how [[spoiler:the Xeelee have no hope of defeating the photino birds - in fact, with time travel, they can barely ''escape'' the Photino Birds, after many resets.]].
* HordesFromTheEast: To the Romano-British featured in ''Coalescent'', the Saxon barbarians that come from the North Sea are this.
* HorseOfADifferentColor: In ''Gravity Dreams'', the space whales are seen used as mounts by a group of barbarians.
* HowDareYouDieOnMe:
-->'''Regina:''' No! No, you sow, you bitch, you cow, you whore, Cartumandua! You won’t leave me, not you, too, you slave, not now!
* HumanResources: On the ''Mayflower'' generation ship, all dead human bodies are recycled for raw materials, since on such a closed-out environment, burial, cremation or other ways of DueToTheDead are luxuries that cannot be afforded.
* HumansAreDivided: Humans are the only race that fight their kinsmen on a regular basis.
* HumansAreTheRealMonsters: It is hard to consider the Coalition as anything but the villains of the Third Expansion. They murdered every single piece of sapient life they came across that was not human. The Silver Ghosts and the Xeelee have no interest in fighting the humans, but they stand in the path of humanity’s expansion.
* HumansAreWarriors: In spades, at least once the "[[NonindicativeName Interim Coalition of Governance]]" comes into power. The Xeelee outclass Humans in pretty much every sphere of technology, but the FantasticRacism of Mankind's "Third Expansion" era doesn't let a little thing like ''that'' stand in the way of galactic conquest. A line in ''Exultant'' expresses humanity's tenacity as such:
-->''To the Xeelee, we were little more than rats - so that's what we became. Tenacious, relentless, swarming; fighting an interstellar war with teeth and nails.''
* HumansThroughAlienEyes: Half of ''The Sun-People'' is told from the point of view of a Toolmaker alien whose homeworld is first visited by the humans during the story. The alien refers to humans as the 'Sun-people', bizarre, otherworldly and seemingly destructive creatures that ultimately turn out to be benevolent.
* HumanSubspecies:
** In ''Flux'', humans have been modified to microscopic lifeforms to live within a Neutron Star.
** [[spoiler:In the turbulent centuries between Regina's time and ours, the Order keeps itself hidden and so separate that natural selection has the time and the opportunity to take effect, and the Order's members are nudged onto a divergent evolutionary path. Over time, living in the dark, the society develops a hypersensitivity to pheromones. Space is strictly limited, so the right to bear children is tightly controlled; delayed puberty becomes a desireable trait, as does adaptation for bearing multiple children at once. The same traits are observed in workers and queens, in eusocial species.]]
* {{Hypocrite}}: According to the Druz Doctrines, the official ideology of the Interim Coalition of Governance, unmodified humans are the best, humans should not use Anti-Senescence technology or any other useful self-modification they could do that would make the war easier and life better. [[spoiler:The top ranks of the regime are total hypocrites about the Druz Doctrine, using extensive cybernetic modification, making themselves immortal while banning it for everybody else, and actively making use of immortal pharaohs, eusocial transhumans and alien symbionts.]]
* IDidWhatIHadToDo: From the point of view of the Gemo Cana, she accepts that in helping the Qax with their Extirpation the pharaohs are doing violence to the past, but insists on the need to collaborate, to destroy all records, to be able to keep a continuity through their memory that will enable further independence and defiance.
* ImAHumanitarian:
** The big secret of [[spoiler:the Boneys]] in ''Raft''.
** On the ''Mayflower'', the [[spoiler:subhuman descendants of the long-lived Autarchs]] turn to cannibalism after [[spoiler:breeding immortality into themselves and no longer seeing children as a way to preserve their genes, but simply as food]].
* ImmortalityImmorality: The increased intelligence and longevity of the pharaohs come along with callousness, a ruthless push to do whatever it takes to serve power or hold onto power yourself, all under the justification that this will provide greater insight to guide humanity's future. Yet such justifications ring hollow, as it's not the schemes of the pharaohs that ends Qax rule, any more than it's the Friends of Wigner. Instead it's Jim Bolder's rash, daring, individual subversion of the system that succeeds, while in the following eras, the immortals, the pragmatists, help perpetuate destructive patterns of domination that last far longer than alien rule.
* InsufficientlyAdvancedAlien: The HiveMind StarfishAliens known as the Squeem conquer Earth, despite being no more intelligent and not much ''older'' than humans. How? They lucked out on finding technology left over from the [[SufficientlyAdvancedAliens sufficiently advanced]] [[{{Precursors}} Xeelee]].
* IntangibleMan: [[spoiler:Michael Poole]] after the encounter with the "Anti-Xeelee".
* InTheFutureHumansWillBeOneRace: The Qax invoke this trope to homogenise humanity as part of their Extirpation to erase human culture and history.
* KingBobTheNth: The Empire of Sol is ruled by a dynasty of empresses all named Shira; the Empress during the events of ''Starfall'' is Shira XXXII. [[spoiler:In truth there's no dynasty, mother or daughter here: all the Empresses are the same person, Shira, the Friend of Wigner trapped in the past, as shown in ''Timelike Infinity''.]]
* LaserGuidedAmnesia:
** Michael Poole erases the events of [[spoiler:his destruction of the Titan ecosystem]] from the memory of Miriam Berg, who opposed the act, to keep her quiet.
** After the Squeem [[spoiler:temporarily freeze all of Earth's water, killing many humans and nearly sterilising the oceans in the process]], they engineer a virus to erase all memory of this event from all humans. They mostly succeeded; [[spoiler:all but one human come out of it believing the oceans have always been depleted of life]].
* LensmanArmsRace: The Xeelee use cosmic strings to build a [[OurWormholesAreDifferent wormhole]] (dubbed by humans as "Bolder's Ring") in order to [[spoiler:escape into another universe]]. The Ring is so massive that it's gravity well is pulling in ''galaxies'' from all directions towards it at high speed. The Xeelee's antagonists one up on this by meticulously [[spoiler:arranging galaxies around the Ring in just the right pattern to form a gravitational resonance that will shake the Ring apart]].
* LightWorlder: The inhabitants of the generation ship ''Nord'' have slim bodies, arms only a little shorter than legs, and long toes, not as long as fingers but capable of grasping and manipulation - a body built for zero gravity.
* LivingRelic: Following the Qax occupation, this is the argument used by the pharaohs (humans who collaborated with the Qax and were gifted immortality in return) to dissuade the new human government from killing them: they have become the last keepers of the history and lore of humanity and the planet Earth, which were largely erased during the Qax's Extirpation.
-->'''Gemo Cana:''' Everything humans know about the Xeelee today, every bit of intelligence we have, was preserved by the pharaohs. I refuse to plead with you for my life. But I am concerned that you should understand. We pharaohs were not dynastic tyrants. We fought, in our way, to survive the Qax Occupation, and the Extirpation. For we are the wisdom and continuity of the race. Destroy us and you complete the work of the Qax for them, finish the Extirpation. Destroy us and you destroy your own past – which we preserved for you, at great cost to ourselves.
* LivingShip: The Spline are immense, space-faring creatures who engineer themselves to be spacecraft and then hire themselves out to other species.
* LongevityTreatment: Anti-Senescence technology, which repairs genetic damage due to age via nanobots. The treatment has a 99% success rate, though failures typically end with a terminal illness. Lifespan with AS treatments theoretically has no upper limit, though in practice the treatments begin to break down at 400-500 years.
* LongLived: No pharaoh is truly immortal; it's just that they couldn't foresee a time when they would die, and count their lives in tens of millennia or more. The most enduring of them, Luru Parz, lives for nearly 1 million year.
* LongLostRelative: George Poole only learns about the existence of his twin sister Rosa when he's 45 years old, after his father's death.
* TheLostLenore: Lora, the girlfriend of Rusel, protagonist of ''Mayflower II''. When the Coalition forces reach their home, he is chosen to escape on a generation ship and she is forced to stay behind to be killed, but he never stops thinking about her for the rest of the story.
* LukeNounverber: The primitive people of the jungle on the ''Great Northern'' have names like Arrow Maker, Spinner-of-Rope, Trapper-of-Toads and Painter-of-Faces.
* MadGod: [[spoiler:The [[DeityOfHumanOrigin Transcendence]] ultimately desires to erase all suffering in the past, thereby ensuring that every human that could have existed does so. But since this is seen as too great a task, the Transcendence is prepared to reach back in time and stop humans from ever existing, thereby "erasing" the suffering that they intend to redeem. Now that's a ''messed up'' god.]]
* ManBitesMan: Borno resorts to biting the Black Ghost after all of his crew's weapons turn out to be useless against this creature. [[spoiler:It actually works]].
* MeanBoss: After they are sent to the Belt for mining labour, the scientists are supervised by Roch, a huge, half-mad troublemaker and alcoholic. He doesn't waste any time making life hell for them.
* MechanicalLifeforms: By the time of ''The Siege of Earth'', many old machines abandoned by humans have evolved by themselves and formed rich ecologies.
* MeetTheNewBoss: The day-to-day life of the drones of Conurbation 2473 changes little after the overthrow of the Qax and the three changes in regime - Qax to bandits to Green Guard to Million Heroes - over a year after that. One set of rulers was much the same as another, and the series of ugly power struggles and material erosion makes many people genuinely miss the days of Qax rule.
* TheMigration: The theme of ''The Baryonic Lords'': the migration of the last humans from their dying PocketDimension to Bolder's Ring and there to another universe that can sustain life.
* MileLongShip: The Xeelee Nightfighter has "wings" that stretch out for kilometers, though the cabin is rather small.
* AMillionIsAStatistic: Pirius lampshades this trope after losing two of his close comrades:
-->''And how could he feel so anguished about the loss of two privates, when, if you added up all the losses around the Front, ten billion died every year? It made no sense, and yet it hurt even so.''
* MonumentalDamage: Stonehenge is mostly lost in space near the end of ''Timelike Infinity'', except for a single megalith which becomes a satellite of Jupiter.
* MultiEthnicName: The initial crew of the ''Great Northern'' are named Serena Harvey Gallium Harvey Milpitas, Mark Bassett Friar Armonk Wu, Louise Ye Armonk and Garry Benson Deng Uvarov.
* TheMultiverse: The universe floats in a greater space, called the Bulk, of many extra dimensions. There are many universes floating parallel to each other in the Bulk, like pages in a book. These other universes can be reached through engineering, like wormholes.
* TheMutiny: In AD 415, the Roman soldiers stationed on Hadrian's Wall, having received no pay for five years after the Roman withdrawal from Britain, rebel against and kill their commander Aetius.
* MutuallyAssuredDestruction: In the primordial universe, there were wars between matter-based and antimatter-based life, but they were always so devastating that mutual deterrence became the only option.
* MyFutureSelfAndMe: If you grow up in a Green Navy base, meeting your own future self was no big deal. The whole point of the place is that from birth you are trained to fly FTL starships (or, in other words, time machines). Most people figure out that that means there might come a day when you would meet a copy of yourself from the future — or the past, depending which end of the transaction you look at it from.
* MySpeciesDothProtestTooMuch: Unlike any of its kind, the Black Ghost is a Silver Ghost that fights like humans, with a militaristic hierarchy that proves dangerously capable of fighting humans, using new weapons, tactics and forms of organisation that threaten to turn the tide of battle.
* NeverFoundTheBody: Amator is last seen staying on the surface of Rome before the Vandalic hordes come and sack the city. He is never seen or heard of again after that.
* TheNightThatNeverEnds: The end of ''Vengeance'': [[spoiler:Earth is moved into a new orbit in the Oort Cloud, where the sunlight is a million times as dim. Harry Poole even uses this exact phrase when describing the situation]].
* NoDeadBodyPoops: Implied aversion in ''Raft''. One character sees "a shape hanging from rope" and "a pool of something brown and thick" beneath it.
* NoGoodDeedGoesUnpunished: When a battle turns to disaster for the Coalition forces, Pirius chooses to risk survival instead of following his orders to stand to fight and die pointlessly, in the process capturing a Xeelee nightfighter for the first time in history. Rather than being lauded as a hero, he is court-martialed for disobeying orders.
* NomDeMom: In the Poole clan, a tradition that lasts for many generations is that children inherit their mother's Poole surname - both Michael Pooles took the surname from their mothers Gina Poole and Muriel Poole.
* NoNameGiven: The only aliens that have names are the relatively unimportant Toolmakers (in ''The Sun-People''), Cilia-of-Gold (in the short story of the same name) and the mummy-cows in the Photino Victory stories. Other individual aliens are always referred to by their species, or a title if said alien is particularly important (the Qax governor, the Black Ghost, the Ambassador to the Heat Sink,...).
* NonIndicativeName: The "Interim Coalition of Governance" actually rules humanity for an "interim" period ''over 20,000 years long.''
* NotSoDifferent: Late in ''Exultant'', This Burden Must Pass, a member of the Friends of Wigner cult, has a chat with the Silver Ghost, and people point out a lot of similarity between their world views, but very different implications, with the Ghosts seeking to proactively fix their broken universe, while the Friends are ultimately about acceptance, waiting to be rescued.
* ObliviouslyEvil: The photino birds set out to transform all stars into white dwarfs, which would cause the eventual extinction of all baryonic life forms, including humans. Despite having goals that are hostile to us, photino birds do not seem to be malevolent. In fact, they are most likely unaware that there are baryonic life forms, because their own form prevents them from noticing us at all or realising that the ageing of stars has unfortunate effects to the baryonic universe. Any attempt to communicate them was fruitless.
* ObstructiveBureaucrat: The Coalition is your typical bastion of entrenched, institutionalised mediocrity in which someone might actually be punished for figuring out how to win a war. Thematically, it's a ''reductio ad absurdum'' of much that goes on in modern-day politics. Nearly everyone on the top is hypocritical, short-sighted, repulsive, fears change, and is more interested in holding to their power more than anything else. It is necessary to see how the decision to launch the special weapons project comes about, and a large part of the point of ''Exultant'' is how human institutions prove more of a barrier than even the physical challenges of engineering an instantaneous computer and black hole weapons.
* OlderThanTheyLook: [[FountainOfYouth Anti-Senescence]] treatment makes it difficult to determine the true age of a human.
* OneSteveLimit: Averted. There are two characters named Julia (the mother and one of the granddaughters of Regina), two named George Poole (one of the protagonists of ''Coalescent'', and his ancestor who lived in the 16th century), two named Michael Poole (the protagonist of ''Transcendent'' and his descendant who appears in ''Timelike Infinity'' and ''Ring'') and two named Lora (the girlfriend of Rusel in ''Mayflower II'' and the crush of the eponymous protagonist of ''[=PeriAndry=]'s Quest'').
* OtherMeAnnoysMe: The two versions of Pirius do not get along well with each other.
* OurGodsAreDifferent: The monads, eternal, abstract beings which create each Universe in turn and then sleep through the lifespan of each Universe inside black holes.
* OurVampiresAreDifferent: The bloodsuckers, who are out-of-control Martian Virtuals that learned to steal something far more precious to any Virtual than blood: processor time. There are rules that unnecessary programmes are eventually shut down, but the bloodsuckers can integrate other Virtuals into their own programming and steal their ration of processor capacity.
* OutlivingOnesOffspring: The Qax's gift of immortality to the [[LesCollaborateurs pharaohs]] was ambiguous: they don't breed true and have to watch their children die, if their growth isn't stunted as an infant.
* ParentalIncest: Their shared blood doesn't stop [=MacoFeri=] from siring a child on his own daughter.
* PeopleFarms:
** The army of the Interim Coalition of Governance commands vast birthing crèches to ensure a steady supply of infantrymen. These children are grown in clutches of hundreds and taught the Druz Doctrines to an almost cellular level, ensuring loyalty and every single one of them is trained to kill a variety of aliens in the most efficient way possible.
** The [[spoiler:Black Ghost]] plans to breed a group of captive humans to serve as laboratory animals. [[spoiler:Too bad this plan never leaves the concept stage]].
** The humans of Old Earth are not the owners of the [[spoiler:sentient Weapon machines. The Weapons are farming them like livestock]].
* PersecutedIntellectuals: In ''Raft'', the scientists on the Raft are sent to the Belt to do hard labour after the working class revolts against them and the officers.
* PlantAliens: One of the indigenous lifeforms of the alternate universe where ''Raft'' takes place is a species of mobile floating trees.
* PlotTriggeringDeath: Each narrative of ''Coalescent'' is kicked off by a death: the Roman narrative by the death of Marcus (along with the abandonment of Britain by UsefulNotes/TheRomanEmpire), which forces Regina to move from her family villa; and the modern narrative by the death of George Poole's father, which indirectly causes him to find out the existence of a long-lost sister and begin the search for her.
* PocketDimension: After their defeat by the Xeelee, the human race are locked away in a vast hypersphere bigger on the inside than on the outside, and imprisoned within an artificial world.
* PoorCommunicationKills: Humans start a massive war with Xeelee because they believe that the Ring is intended to wreck the Universe. Unforunately, they discover too late that it's actually [[spoiler:a wormhole created by the Xeelee as the only way for baryonic life to escape extinction at the hands of the unstoppable Photino Birds]]. Similarly, the [[spoiler:Photino Birds]] are so alien that they most likely do not even realise that they are [[spoiler:wiping out untold numbers of species in the process of making the Universe more comfortable for themselves]].
* PopulationControl: On the ''Nord'', you are allowed two children at the maximum. If you have any more, one of the existing ones must leave the ship.
* PostPeakOil: In the 2040s, the depletion of fossil fuels and desperate efforts to contain further environmental damage has made the average person dramatically less mobile, with automobiles a memory, air travel a luxury of the ultra-privileged.
* ProtagonistJourneyToVillain: ''Reality Dust'' details an incident involving reality dust and Pharaohs on Callisto that causes Hama Druz to turn from an abstract-minded bureaucrat into the insane ideologue whose demented 'humans as vicious vermin' philosophy fuels the atrocities of the Coalition and plagues humanity for twenty thousand years.
* PublicDomainCharacter: [[Myth/KingArthur A post-Roman British warlord named Artorius and his genius friend Myrddin]] make an appearance in the Roman narrative of ''Coalescent''. After Artorius' death, the despairing British are left with nothing but legends of how he's not dead, but sleeping, his mighty sword Chalybs at his side.
* TheQuisling: Jasoft Parz, the human ambassador to the Qax occupation regime. He was never loyal to the invaders, and actually betrays them when [[spoiler:they go back in time 1500 years to invade the Earth in the past]], but he's still seen in a negative light by almost all humans of the later eras.
* RammingAlwaysWorks: When every weapon the humans have at their disposal fail to move the Xeelee Probe hurtling towards Earth by any meaningful distance, Michael Poole resorts to ramming his ship (except for the lifedome) into it. Unfortunately, even the force of a GUT drive isn't enough to scratch the Probe's shell made from Xeelee construction material.
* RapidAging: During her brief life as a human, Lieserl's body is engineered by nanobots that cause her to age rapidly. Memories and learning are also implanted into her cortex. The combination of these effects results in Lieserl living the equivalent of a 90-year life in 90 days.
* RealityWarper: The "Snowmen" technology used to protect Earth in the short story "The Siege of Earth" (from ''Resplendent'') seems to at least border on this.
* RecursivePrecursors: The very first of them are the spacetime-defect creatures ([[spoiler:ancestors of the Xeelee]]), who dominated the universe before during the grand unification epoch, which ended 10[[superscript:-36]] seconds after the Big Bang. After them came the quark-gluon based lifeforms, who flourished during the first millionth of a second of the universe. And finally there are the quagmites, who lived for thirty times that period before another cosmic transition lets baryonic life like humans inherit the universe.
* RedSkyTakeWarning: One of the indicators that the nebula in ''Raft'' needs to be evacuated.
* RelationshipSabotage: Regina twice tries to get rid of her daughter Brica's budding romances, first with the FarmBoy Bran and then with the blacksmith apprentice Galba until she's satisfied with her third boyfriend, the Roman freeman Castor.
* TheRemnant: After each universal mass extinction, small enclaves of the survivors would survive in one manner or another, witnessing the universe becoming progressively colder and slower.
* RetCon: In ''The Xeelee Flower'' (the very first story written in the series), the Xeelee seem like an advanced species somewhat similar to humans, having buildings, doors, rooms, handguns, and nightfighters have tiny hand-operated control panels. Later books (from ''Exultant'' onward) depict them as eldritch beings totally bound up with their technology (part spacetime defect symbiotes) such that one can't really distinguish between themselves and their technology.
* RidiculouslyFastConstruction: The construction of a Qax conurbation takes place in just minutes.
* RockBeatsLaser: Despite the extent of the Silver Ghosts' reworking of their physical environment (they frequently toy with the laws of physics to advance their own knowledge), they ultimately lose against the humans, who manage to survive and kill through savage innovation.
* RockMonster: The colonists of the desert planet Baynix II ditched their carbon-based bodies for slower silicon models which leave them resembling motionless, man-shaped monoliths.
* RuleOfCool: Celestial bodies up to and including entire galaxies used as [[ColonyDrop projectiles]]? Megastructures millions of light years across? Handguns that can destroy ''stars''? Aliens altering the value of Planck's constant simply in order to build a faster computer? Creator/StephenBaxter was rocking this trope before it was mainstream.
* ScrewThisImOuttaHere: When the humans attack the Xeelee from the Chandra black hole at the centre of the Milky Way, the Xeelee abandon the black hole because the method that the humans are using to attack them is potentially causing damage to the black hole itself and the monads inside.
* ScryVsScry: Humanity fights a War against the [[StarfishAliens Xeelee]] over the Milky Way Galaxy where both sides can send information backwards in time using [[FasterThanLightTravel FTL]]. In practice, neither side can ever get an advantage. This goes on for [[HopelessWar tens of thousands of years]].
* SecretKeeper: Harry Gage, [[spoiler:hidden away from the Squeem when they conduct their operation to erase all memory of their freezing of the oceans that killed many humans and species, emerges as the sole person who remembers the event. He becomes the first Rememberer, and after his death his successors continue to keep and pass this knowledge until the discovery of a Squeem holdout in the Solar System, and the last Rememberer decides it's time to reveal it]].
* SelfDuplication: Each photino bird is a perfect copy of its parent.
* SelfMadeOrphan: Teeg takes great pride at the moment when he killed his neglectful father, a Foron noble (implied to be [=MacoFeri=]) who had raped his mother, a servant.
* SequelHook:
** ''Timelike Infinity'' ends with this paragraph (which indirectly leads up to ''Ring''):
-->[[spoiler:And then— There was a box, drifting in space, tetrahedral, clear-walled. From around an impossible corner a human walked into the box. A rope woven of bark trailed behind him, out of sight. The human was dressed in treated animal skins. He was gaunt, encrusted in filth, his skin ravaged by frost. He stared out at the stars, astonished. Michael’s extended awareness stirred. Something had changed... History resumed.]]
** ''Formidable Caress'' also ends with one (which leads to ''Vengeance''):
-->[[spoiler:Even after the Xeelee had finally won their war against humanity, the stars continued to age, too rapidly. The Xeelee completed their great Projects and fled the cosmos. Time unravelled. Dying galaxies collided like clapping hands. But even now the story was not yet done. The universe itself prepared for another convulsion, greater than any it had suffered before. And then— ‘Who are you?’ ‘My name is Michael Poole.’]]
* ShadowArchetype: [[AvertedTrope Averted]] with the "Anti-Xeelee", since its name actually refers to the fact it travels backwards in time, like some anti-particles are theorized to do. The antagonists of the Xeelee, the [[spoiler:Photino Birds]], fit.
* ShoutOut: One of the simulations enacted by Martian Virtuals during the events of ''Xeelee: Vengeance'' is named 'Barsoom', and involves mostly naked, red-skinned, egg-laying human-like beings, apparently based on the works of a certain Discovery-era (read: 20th century) [[Creator/EdgarRiceBurroughs author]]. [[Literature/JohnCarterOfMars Sounds familiar]]?
* SiliconBasedLife:
** On Titan, Michael Poole and Miriam Berg find life based on silicon-silicon bonds between silanol molecules dissolved in liquid ethane, and ammono life, based on chemical bonds between carbon and nitrogen-hydrogen chemical groups rather than carbon-oxygen, using ammonia as its solvent rather than water.
** A group of human colonists on a silicon-rich world (visited in ''Transcendent'') encountered indigenous silicon-based life, abandoned their carbon-chemistry medium and chose to download their children into the silicon.
* SingleBiomePlanet: The homeworld of the Qax is a swamp planet, covered from pole to pole by an ocean.
* SlaveRace: After the humans overthrow the Squeem occupation, they bring the fight to the Squeem home system and subjugate their former overlords, who are only allowed to live due to their usefulness as symbionts for humans.
* SonOfAnApe: By the time of ''Exultant'' humanity has converted almost the entirety of the Milky Way into an industrial war machine with which they are engaging in a multi-millenial pan-galactic campaign against the Xeelee. Still, the Xeelee view this as roughly the equivalent of an especially persistent cockroach infestation, and think of humanity as little more than pond life.
* SpaceAgeStasis: The Coalition regime embraces stagnation to preserve human continuity, avoiding political and even most technological change. The imperative commitment to total war stagnates human physical and intellectual evolution. The Druz Doctrines do not encourage exploration or research, and very little effort is directed toward projects without an immediate and conspicuous benefit to maintaining the massive logistics necessary to continue the Xeelee war. From hundreds of thousands of years later human historians note that the Coalition was freakish in how cohesive, unified and stagnant they were.
* SpaceWhale: The Spline are [[LivingShip giant living armored spaceships]] that evolved from alien whales. They live off interstellar gas and other species use them as transports and warships. There are also more literal space whales that inhabit the alternate universe where ''Raft'' takes place.
* StableTimeLoop: It's eventually revealed that the Xeelee [[spoiler:sent themselves back in time to supercharge their own development]]. Then it turns out [[spoiler:the Photino Birds can go one better. They do this ''naturally and at will'', even from the end of the universe back to the beginning.]]
* StarfishAliens: Pretty much every single race in the series. There's almost nothing remotely human-like, aside from humanity's descendants-- [[TranshumanAliens if then]].
* StarKilling: The Xeelee starbreaker gun is aptly named indeed. This is also the goal of the photino birds, who seek to turn all stars in the universe into white dwarfs.
* TheStarsAreGoingOut:
** Due to the photino birds' interference, the stars are aging far, far faster than they should, and in 5 million years - rather than 100 trillion - almost all the stars in the universe will become white dwarfs.
** In ''Gravity Dreams'' (a sequel to ''Raft''), the alternate dimension Beta's Stelliferous Era is coming to an end, and the humans stranded there need to be evacuated.
* StarterVillain: The Squeem, the first aliens that pose a true threat for the humans. They manage to conquer the Solar System and enslave humanity for 51 years, but it later turns out that they are not especially intelligent or advanced, and are dependent on scavenged technology from the Xeelee, like the hyperdrive. After the overthrow of the Squeem, the humans gain access to Xeelee technology for the first time, which opens up a new expansion era, while the Squeem themselves become DemotedToExtra.
* SufficientlyAdvancedAliens: The Xeelee are sufficiently mysterious in-universe that no one is sure what they really are. Though their actual power far exceeds many other examples that are the traditional sufficiently advanced alien, in many of the earlier short stories the reader is given the impression they are normal biological lifeforms. This is simply because their godlike technology is still recognizable as such and uses comprehensible interfaces, if not comprehensible principles; they're a hyper-extreme example of HigherTechSpecies instead. However:
** There are indications that Bolder's impression of the Xeelee were retconned, or at the very least the Nightfighter he piloted was a second-hand cast off, like so much of Xeelee technology. In ''Exultant'', it is revealed that the Xeelee are self-aware space-time constructs that have existed since very earliest moments of the universe.
** The Anti-Xeelee definitely ''is'' sufficiently advanced, in a DeusEstMachina sort of way.
* SuicideAttack: During the Squeem occupation of Earth, a human assassin, pumped full of Squeem-specific toxins and pathogens, jumps into the Squeem colony of Lake Superior laden with rocks, slits her own wrist and lets her blood fill the lake to exterminate the colony.
* SuperBreedingProgram: Garry Uvarov's eugenic program, which aims to improve the human stock by getting rid of late acting lethal genes, which normally could never be selected out of the gene pool because they only kill old bodies after they have reproduced. Uvarov orders his followers to live as hunter-gatherers in the sealed off forest, abandons Anti-Senescence treatments and bans reproduction before the age of 40, with this limit being steadily raised over the years. After eight centuries, the jungle folk's average lifespan goes up from 100 to 250, with the 80-year-old Arrow Maker being in the prime of life.
* SuperPersistentPredator: The Squeem missile sent to destroy an asteroid engineered by some humans to be an escape hatch off the occupied Solar System in ''Pilot''. Among the pursuit, the missile adapts itself to accelerate faster, the humans have to modify their ship to do the same. This continues on, moving significant distances for what is millions of years outside due to time dilation. By the time they manage to crash the missile into a black hole, the humans have abandoned their physical forms, and Squeem rule over humanity has long since ended, that the chase continues past the point where there are probably any other humans still alive.
* SupervillainLair: The HQ of the Black Ghost, a sphere black as night and kilometres across.
* TheSymbiote: A Silver Ghost is a community of symbiotic creatures: an autarky, a miniature biosphere in its own right, all but independent of the universe outside.
* TakenForGranite: The microscopic aliens from Beta Pegasi are able to force carbon dioxide into a form of silicate-like rock that superficially resembles chalk.
* TeleFrag: When the reality dust entities shifted Callisto virtually instantaneously a few thousand kilometres or so, a Xeelee was killed by being trapped under the ice (a method that seemed to act by both encasing the Xeelee in the ice and impaling it because Callisto suddenly occupied the same space the Xeelee was in).
* ThatsNoMoon: Encountered by the humans during their mission to assassinate the Black Ghost:
-->''The wall behind Hex’s back suddenly gave way, and she was tipped onto the cold ground. When she looked up she saw that the ‘sandbags’ were suspended in the thin air, heavy, rippling sacks swarming over her head. There must have been fifty of them, more. This ‘wall’ had a been a reef of [[spoiler:ur-Ghosts]], huddled together.''
* ThirdEye: The space whales of Beta have a total of three eyes.
* ThirdPersonPerson: Quid from ''Raft''.
* TimeAbyss: The traitorous humans who collaboratorated with the alien who conquered Earth were given eternal life as a reward. They eventually begin [[WhoWantsToLiveForever to regret this]].
-->''My name is Luru Parz. I was born in the year AD 5279, as humans once counted time. Now I have lived so long that such dates have no meaning. We have lost the years, lost them in orders of magnitude.''
* TimeDilation: Frequently, due to the prevalence of ships that move close to the speed of light: the ''Great Northern'' is designed to undergo a journey that will take 1000 years for its crew to return to Earth in AD 5 million. In Old Earth, a world with stratified time, time runs faster the higher up you climb, leading to the longer-lived upper crust living at the bottom exploiting the (relatively) short-lived caste further up, and passes much more slowly than outside, so its inhabitants can live off the trickling geothermal heat of the Earth alone, to the point that the gaps between the stories are measured in ''hundreds of millions'' of years.
* TimeSkip:
** The first part of ''Ring'' ends with the launch of the ''Great Northern'' in AD 3951. The second part starts after nearly a thousand subjective years on the ship, which equals five million years outside due to time dilation.
** The Roman narrative of ''Coalescent'' starts in AD 410 and skips a few years every several chapters.
** Each chapter of ''The Venus Generations'' take place a century after the previous one.
* ToServeMan:
** ''Breeding Ground'' ends with [[spoiler:the protagonist being consumed from inside-out by her Squeem symbiont]].
** In ''The Lowland Expedition'', [[spoiler:the living buildings of the unnamed city feed on the humans that stay inside them]].
* {{Transhuman}}: The various species of Weaponised, modified from humans by scientists of the Integrality.
* TrappedInThePast: By the end of ''Timelike Infinity'', [[spoiler:Jasoft Parz and Shira, two humans from AD 5407, are trapped in AD 3717]].
* TreeVessel: In ''Raft'', one of the strange lifeforms in the high-gravity universe is a species of mobile floating trees. Humans turn them into vessels and steer them through space.
* TykeBomb: The Coalition makes use of Child Soldiers, many of whom are grown in vats at the Front. Each of these children are taught the Druz Doctrines to an almost cellular level, ensuring loyalty to the cause and every single one of them is trained to kill a variety of aliens in the most efficient way possible. Every Child Soldier is sent into battle when they are ready, often with special augmentations to suit their job.
* UncannyValley: In-universe. Rusel finds the [[spoiler:inbred, savage descendants of the [[WasOnceAMan Autarchs]]]], with their blank eyes and wizened-faced children, peculiarly disturbing.
* UnPerson: The alien Qax attempt to do this to the entire history of humankind, in a project know as the "Extirpation", in order to make humans more docile slaves.
* VertebrateWithExtraLimbs: The spindlings of Old Earth (which were originally aliens that were brought to Earth) have an inner skeletal structure but differ from native Earth tetrapods in one way: they have six legs. The creationists on the world uses this detail to justify their hypothesis (which is actually correct).
-->''Like most primitive cultures on the Shelf, you Forons cling to a naive naturalism! You believe that the world as we experience it emerged from the blind operation of natural laws, that intelligence had no hand in it. But ''that cannot be true''. The spindling is ''proof'' that the world could not have developed organically; one counter-example is enough to demonstrate that nature lacks the necessary unity for that to be so. The simplest hypothesis is in fact that it has ''all'' been made, all shaped by intelligence, from blueshifted sky to redshifted Lowland.''
* VestigialEmpire: The Roman narrative of ''Coalescent'' is set in Britain from AD 410 (the year the Romans withdrew from Britain) to AD 455, and in Rome from AD 455 (the date of the second Sack of Rome by the Vandals) to Regina's death in AD 476 (the end of the Western Roman Empire). The filth and decay of civilisation, the rapid decline of cities, withering of trade, decline of population and the loss of education and skills; or in other words, the rapid onset of the Dark Ages in just a couple of generations, is described in vivid detail.
* VichyEarth: Earth is occupied twice by aliens, first by the Squeem from AD 4874 to AD 4925, and later by the Qax from AD 5088 to AD 5407.
* VillainProtagonist: The protagonists in ''The Ghost Pit'' are perhaps the vilest in the whole series. In other stories, the worst cruelty is done by child soldiers in pursuit of collective victory, it's appalling, but somewhat understandable, and don't seem as individually perverse. In this story we see the hunting down of the last Silver Ghosts, not for fanatical conditioning, nor the belief in xenocide necessary for human survival, and not even motivated by ideology. Instead it's two people who want to do it for individual profit, and even more to be able to take out the last Ghosts. It's repulsive in a way that's not common even to this monstrous era.
* VirtualGhost: Virtuals, basically a copy of a living human's personality stored in a computer. Many of them inevitably outlive the original humans.
* TheWarOfEarthlyAggression: ''Starfall'' documents the preparations and events of the Starfall rebellion conducted by the human extrasolar colonies against the Empire of Sol, based in New York.
* TheWatcher: At some point of their evolution, the Snowmen turned themselves completely toward the philosophy that to record events - and only to record - was the highest calling of life. They took apart their world and rebuilt it as a monstrous storage system. They used all the material at their disposal to freeze as much data as they could in an artificial structure called the Snowflake, making near-optimal use of matter, by recording information right down to the thermodynamic limit set by the background temperature of the Universe. As the universe cools down they can store more data.
* WaveMotionGun: The Xeelee starbreakers, which shoot focused gravity waves that can tear apart stars or cause them to go nova, certainly qualify. By the time of ''Exultant'', humanity also uses guns which fire magnetic monopoles and later black holes.
* WeAreAsMayflies: Hama Druz's doctrines actively invoke the 'humans as short-lived vicious vermin' mentality. The slogan most associated with that and endlessly repeated in the stories of this era is "A brief life burns brightly." That is, it's better to have a short and violent existence in the face of endless war than a longer, happy and more settled life. The Coalition's approach makes the Stalinist New Man look Epicurean by contrast.
* WeAREStrugglingTogether: ''Conurbation 2473'' shows the typical human reaction to their suppressive Qax dictators suddenly fleeing Earth, leaving humans free for the first time in centuries. Rather than banding together to rebuild society, humans fight among themselves for dominance (such as what takes place virtually everywhere in the world nowadays).
* WeHaveReserves: The Coalition's Child Soldiers are more or less similar to modern teenagers, aside from the fact that they are artificially grown in clutches of hundreds at a time and become fertile at a much younger age. As a result of this, the Coalition loses over 10 billion Child Soldiers a year to the Xeelee. It's their duty to die. Not to ''fight'' for humanity, but to die. According to their "A brief life burns brightly!" ideology, there is nothing as glorious as child soldiers dying for the sake of dying.
* WeWillUseManualLaborInTheFuture: The Coalition's Green Army forces their soldiers to dig their own trenches even if it's more efficient to let machines do it, in order to reinforce their superstition that a shelter constructed by a machine will never be as safe as one you have dug out yourself.
* WhatASenselessWasteOfHumanLife:
-->'''Nilis:''' That means that ten billion people a year are sacrificed on the Front, Pirius. The number itself is beyond comprehension, beyond empathy. ''Ten billion''. That’s more than three hundred every single second. It is estimated that, in all, some thirty ''trillion'' humans have given their lives to the war: a number orders of magnitude higher than the number of stars in this wretched Galaxy we’re fighting over. What a waste of human lives!
* WhatTheHellHero: [[spoiler:Jovik Emry]] gives one to [[spoiler:Michael Poole]] after [[spoiler:Poole destroys the Titan ecosystem and edits the memory of Miriam Berg, who opposed it, to make her forget]].
-->[[spoiler:What will you make her believe – that she stayed up on the Crab with Harry the whole time, while you went exploring and found nothing? That would work, I guess. I think you love her. I even think she loves you. Yet you are prepared to mess with her head and her heart, even her personality, to serve your grandiose ambitions. Let me tell you something. The Poole she left behind in that pocket universe – the one she said goodbye to – he was a better man than you will ever be again. Because he was not tainted by the great crime you committed when you destroyed the cavern. And because he was not tainted by ''this''. And let me make some predictions. No matter what you achieve in the future, Michael Poole, this crime will always be at the root of you, gnawing away. ''And Miriam will never love you again.'' Even though you wipe out her memory of these events, there will always be something between you; she will sense the lie. She will leave you, and then you will leave her. One thing I know better than you is people, and what goes on in their hearts. You remember I said this. And, Poole, maybe those whose work you have wrecked will some day force you to a reckoning.]]
* {{Xenofiction}}: A few of the short stories set in the Expansion era in ''Vacuum Diagrams'' are partially told from the point of view of the aliens.
* YouALLLookFamiliar: [[spoiler:The degenerate descendants of the mortal transients on the ''Mayflower'' all resemble to some degree Lora, the dead girlfriend of the last living pharaoh Rusel. In an attempt to curry favour with Rusel, the transients are breeding themselves into replicas of Lora's images: if the Elder loved this woman so much, then choose a wife that looks like her, if only a little, and hope to have daughters with her delicate looks, and so win favour.]]
* YouCannotGraspTheTrueForm: In some interviews when asked about it, Baxter says any human attempts to comprehend Xeelee 'culture' and 'society' would be equal as an ant somewhere in Africa trying to comprehend workings and behaviour of the UN.
* YourCheatingHeart: [[spoiler:The second child of Michael and Morag Poole, who killed her during childbirth, is not Michael's at all.]]
* YouGottaHaveBlueHair: Vander Guthrie, a victim of a genetic engineering mishap, has sky-blue hair.
* YouKilledMyFather: Harry Gage opposed the Squeem to the end of his life for their murder of his parents.
* YouNoTakeCandle: In ''In the Un-Black'', the language of the savage post-humans, which has 'devolved into jabber', is represented by broken English: 'un-' replaces 'no' and 'not' as negative particles (hence 'the Un-Black'), and some verbs have been replaced by nouns used as if they were verbs ('to death' instead of 'to die' or 'to kill', 'to crime' instead of 'to commit a crime', among others).
* ZergRush: The only tactic that the Coalition is able to use against the Xeelee is to throw endless warm human bodies at them, suffering staggering casualties for little to no gain.
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