Six million years ago, at the very dawn of the starfaring era, Abigail Gentian fractured herself into a thousand male and female clones: the shatterlings. Sent out into the galaxy, these shatterlings have stood aloof as they document the rise and fall of countless human empires. They meet every two hundred thousand years, to exchange news and memories of their travels with their siblings. Campion and Purslane are not only late for their thirty-second reunion, but they have brought along an amnesiac golden robot for a guest. But the wayward shatterlings get more than the scolding they expect: they face the discovery that someone has a very serious grudge against the Gentian line, and there is a very real possibility of traitors in their midst. The surviving shatterlings have to dodge exotic weapons while they regroup to try to solve the mystery of who is persecuting them, and why - before their ancient line is wiped out of existence, for ever.
Amazon: Average: 4.3. Mode: 5 stars.
Goodreads: Average: 4.03. Mode: 4 stars.
House of Suns is space opera on a grand scale: the Gentian line, "shatterlings" cloned from Abigail Gentian six million years ago, makes circuits of the entire galaxy in kilometers-long sub-light ships, collecting information, watching civilizations rise and fall, building Dyson sphere-like constructs to contain supernovas, making deals and occasionally feuding with other clone lines, and meeting up for a big family reunion every two hundred millennia.
It helps to have a rudimentary grasp of Special Relativity when reading this book. While the Gentians are immortal and millions of years old in objective time, between stasis and time dilation they actually only experience a fraction of that time. The way special relativity works plays an important part in several scenes involving spaceships that can accelerate to near-light speed (but not supra-light) pursuing each other, and also in the climax.
Aside from a machine civilization, humans are the only sapients in the galaxy, though there is evidence of a "Prior" civilization. On the time scale of the galaxy, it's not all that unlikely that a sapient species could evolve, expand, and then go extinct in the space of a few million years, with huge gaps between such species. Thus, the civilizations that the Gentians encounter are all descended from humanity, though posthuman evolution has transformed many of them into forms that might as well be alien.
Oh, and at some point a big event known as "the Absence" occurred: the Andromeda galaxy (apparently) winked out of existence. This is a minor (story-wise) mystery mentioned early on; naturally, it proves to be significant later.
The main POV characters are Campion and Purslane Gentian, male and female clones of Abigail Gentian. As the story begins, they are traveling together on their way to the next big Gentian family reunion. The two of them are expecting to catch hell from their family for two reasons: first, due to various circumstances, they're going to be about fifty years late, which even on the Gentian schedule is tardy enough to merit censure. But worse, the two of them have fallen in love. This is apparently a big no-no, and considering how significant it was in the story, I found the reasons unconvincing.
While I can understand why dear old Abigail (who is also a POV character in a minor way, as we see a number of flashbacks showing certain critical events of her childhood that led to the creation of the Gentian line and interstellar civilization) might have been squicked by two of her clones boinking (one wonders how incest laws will cover this when we perfect cloning), her shatterlings are going to be around for a long, long time, and they are still human. One would think such an ancient, parochial taboo would fade eventually (especially since the other clone lines aren't exactly friendly).
"Fortunately" for Campion and Purslane, it turns out their family has bigger things to worry about. When they approach the reunion site, they receive a message informing them that unknown attackers ambushed the Gentians and slaughtered all but a handful. The survivors must now determine who wanted to exterminate their line, and why.
House of Suns is both hard SF and epic space opera, combining two of my favorite kinds of sci-fi, but despite the vast distances and time periods spanned by the novel, it never quite lived up to its epic potential, in my opinion, and that's even when considering the ending. The family intrigue of the Gentians eclipses the ancient civilizations rising and falling around them, genocide, and a conspiracy millions of years old. Campion and Purslane's relationship is realistic, but it's just a plot point, and they never stood out as individuals. I was more impressed by Reynolds' plotting and worldbuilding than by his character development.
Reynolds seems to write a lot of big hard SF space operas with a transhumanist slant. I liked this one, but I didn't quite love it. The reviews suggest that House of Suns is not widely considered to be his best work, so I will probably try one of his other novels to see if it makes me a fan.
Verdict: An epic scale and an engaging plot, marred only by slightly lackluster characters. If you like this kind of hard SF, you should enjoy the book.