House of Suns

House of Suns is a novel by Welsh Sci-fi author Alastair Reynolds, set in more or less the same universe as the novella Thousandth Night -- tropes are listed here for both.

Six million years in the future, the entire galaxy is a Used Future. Tens of thousands of human civilizations have risen and fallen; the galaxy's been united under a single banner too many times to count. In the face of deep time, each galactic federation always falls. No one group endures.

Except the Lines.

Individually known as "shatterlings", the Gentian Line is composed of slightly under a thousand clones made from a woman who lived in the 31st century. They individually roam the galaxy, flitting from star to star near the speed of light, skipping over the ages via Time Dilation. Their purpose is the explore and catalogue civilizations, and every 250,000 years or so they all come together once again to share their experiences and coalesce their knowledge. They've existed for the past six million years, witness to the constant grind of civilization.

Campion and Purslane are two shatterlings who're running late to the most recent Line reunion, having been delayed by an unwanted and dour guest. On top of this, they've been secretly commiting the crime of being monogamous lovers (against the Line's traditional panamory) and traveling together (frowned on as against the "spirit of chance and adventure" in taking unique paths), and they need to edit their travelogues before they get to the Line reunion. As they rush to drop their guest off with the mysterious "Vigilance" civilization, they are sidetracked by a shady ship-dealer who attempts to kidnap them and dissemble their ship for parts. They manage to outwit him and in the process rescue an amnesiac android named Hesperus, a member of the relatively long-lived and advanced Machine People. Returning him to his people would put the Gentian Line on very good terms with them, so Campion and Purslane see him as a scapegoat they can use as an excuse for their lateness to the Reunion. After all, how can you punish tardiness when they've brough such an eminent guest?

Things aren't quite what they seem, however. Hesperas is discovered to be partly human underneath his metal exterior, a fact that even he can't explain due to his amnesia. And Dr. Meninx mysteriously dies during their journey to the reunion. But the worst of all is when they get to the Reunion system...and find it utterly wiped out.

Someone is attempting to wipe out the line. Someone who has intimate knowledge of the Line's secrets, and due to the sheer timescales involved, must keep a very long grudge.

Tropes used in House of Suns include:

A.I. Is a Crapshoot: Subverted: In the past, a robot culture emerged. Humanity, fearing this trope, created a virus which was designed to only kill the robots on command, not before. The virus malfunctioned, though, and the result was genocide. The titular House of Suns erased this event from history and work to keep it under wraps.
Alien Sky: The world that the novel starts on has a special atmospheric bubble which, at night, amplifies faint stars and nebulae, creating a very colorful night sky.
Artificial Gravity: Used by the starships to propel themselves and to protect their occupants from the crushing force of their thrust.
Big Dumb Object: The Vigilance.
Body Horror: The far-future torture technique called 'sectioning'.
Cool Starship : The Silver Wings Of Morning. Basically, the starships from the Revelation Space series turned Up to Eleven -- they've had a lot more time to perfect and evolve the technologies involved than RS folks do.
Creative Sterility: The original Machine People couldn't create art, but were fascinated by it.
Deflector Shields: Used throughout the novel. A ubiquitous technology during the time of the novel. Also used for intertial dampening, as a ship's shields can be projected internally around its inhabitants, allowing extremely high-g maneuvers that would normally render everybody inside to jelly.
Dyson Sphere: The Gentian Line's stardams, which can contain a supernova.
Floral Theme Naming: Gentian Line is known as the "House of Flowers", uses a five-petalled flower as their symbol, and all of the shatterlings in the Line are named after angiosperms (some more obliquely than others).
Endangered Species: Though not a "species", per se, this is pretty much what happens to the Gentian Line. They went from 1000 members to only fifty after the initial attack on them, and with someone actively gunning for them, they are in real danger of being wiped out forever.
Faster-Than-Light Travel: Zig-zagged:Almost all travel is by slower-than-light ships, but at the end of House of Suns a Prior artifact allows for FTL travel (and implies a lot more FTL trips in the past).
Ghost Planet: Implied to be very common throughout the galaxy. Since the various descendants of humanity have been cavorting around the galaxy for the past six million years, there are plenty of planets that once played host to technological civilizations only to leave nothing behind but ruins.
Humans Are the Real Monsters: In House Of Suns, the Lines come into contact with a curious, benign robotic civilization spawned from human technology. The Lines develop a virus to disable the robots if they pose a threat to human civilization, triggered remotely. Except, The virus suddenly goes off and begins wiping out the civilization, and the Lines desperately cover it up by ignoring the robots, and then cover it up, by wiping out entire human civilizations and indvidual Lines.
The Fog of Ages: The long-lived protagonists, considering they've lived through six million years (though, admittedly, only a couple tens of thousands of those concious). They routinely re-arrange/edit their memory. It's implied that they could hold all of their memories at once, if they wanted to, but having that many memories would affect their personality so drastically that most choose not to. Most the long-lived characters tend to hold a rough cliff-notes version of their memories in their heads, but not any of the details; the main character Campion intentionally prioritizes his "recent" memories, which in part drives the main plot.
Humanity's Wake: Due to the sheer number of civilizations that have come before, it seems you can't go anywhere in the galaxy without bumping into some planet that was colonized, terraformed, rose to prominence, became the center of a galactic civilization, then died out, leaving the ruins to be colonized again by whatever evolved in the three million years that has passed...
Hyperspace Is a Scary Place: Well, wormholespace anyways.
Laser-Guided Amnesia: Becomes a major plot point. See also The Fog of Ages entry above.
Mechanical Lifeforms: The Machine People, a race of human-looking androids with a little bit of clockwork features thrown in for flair. Despite having been around for millions of years, undergoing their own Mechanical Evolution, there's still people who think of them as nothing more than mindless automatons who just imitate sentience.
Opposite Gender Clone: Half the members of each of the Lines.
Portal Network: The First Machine that Campion meets tells him that there are wormholes throughout the Andromeda galaxy which lead to different galaxies throughout the universe. It also speculates that the 250-million-light-year-wide Boötes void [1] could actually be full of galaxies connected by wormholes, but that each galaxy is otherwise blocked from the rest of the universe so they can use their wormholes for pseudo-FTL travel without violating causality.
Precursors: The Priors.
Reactionless Drive
Really Seven Hundred Years Old : The Shatterlings are about 6.4 million years old, though "only" a couple hundred thousand of those are spent awake.
Rubber Forehead Aliens: Played with, as the entire (quite diverse) population of the Milky Way Galaxy can trace its ultimate ancestry back to Earth.
Send in the Clones: The shatterlings are all clones of Abigail Gentian or other humans in the far past (who particularly is what defines a Line); however, they've all been slightly modified, and some are male, so there's some variation. Better to think of them all as siblings who remember being the same child.
Shout-Out: This book is pretty much every single Alan Parson's Project song title smashed into a Space Opera screen play.
Space Opera: And how!
Stern Chase: Across 60,000 light-years of interstellar space.
Teleport Interdiction: How the Silver Wings Of Morning is hijacked.
That's No Moon: The protagonists stop at a ringed gas giant because they heard about a spaceship salesman who lives there. They enter the atmosphere and find that he only has a few ships to sell. After some coercion, he shows them his entire collection of ships, which were hidden inside and disguised as part of the gas giant's ring system.
There Is No Kill Like Overkill: When the shatterling's reunion world is destroyed by the entities trying to wipe out the Gentian Line.
- The world is bombarded from orbit and it's atmosphere is boiled off from the sheer energies of the onslaught. Normally that'd be enough to kill anyone, but the aggressors just keep on going, continuing to bombard the planet until the crust melts completely. They still keep on going, pumping so much energy into the planet that it literally just expands from the heat and disintegrates in a slow-motion kaboom.
Time Dilation: The main reason the Gentian Line has persisted for so long. Also, an unavoidable consequence of pretty much any kind of space travel, since if you want to get anywhere in a reasonable amount of time (read: within a couple thousand years), you pretty much have to crank up the g's until you're near lightspeed.
Unusual User Interface: Palatial, a sort-of holodeck. It's a small room, but as you walk in you are immersed in a vibrant, computer-generated world. Your brain is continually scanned while you are in it, so the world constantly adjusts and changes according to your wishes.
Used Future: The ships used by the Gentian Line are often millions of years old. There are also millions of planets lying around that have been terraformed, then left forgotten, then rediscovered and colonized, then forgotten, then rediscovered...
What Happened to the Mouse?: The minor character at the beginning of the novel, Dr. Meninx, who is the unwelcome guest that delays the main characters at first, setting off the whole plot. He dies mysteriously during a voyage, after previously acting afraid of Herperus and evasively implying that he had reason to want to kill him. However, it's revealed that Hesperus didn't murder him, so the characters start to trust Hesperus...and the fact that Dr. Meninx died in the first place is never brought up or questioned again. Literally the whole point of his death was to temporarily cast suspicion on Hesperus, in order to further the plot slightly.