Blindsight (2006) by Peter Watts is a First Contact story. It's also a discussion on what it means to be human, and whether one needs sentient self-awareness to be considered intelligent. This is not as densely written, nor in my opinion quite at the level as its successor novel Echopraxia, but still pretty good.
In the latter part of the twenty-first century, technology is advancing quickly. Most people get enhancements of various sorts, whether genetic or cybernetic. Weaponized viruses have been released and are attacking swaths of the population. Some people choose to "go to Heaven", where in exchange for putting their bodies into a permanent medical coma, they get to live a godlike life online.
Another technological advancement is the resurrection of extinct species, like the dinosaurs in Jurassic Park. But the most remarkable revival is that of "vampires", a hominid offshoot that is far more intelligent and quick than homo sapiens. Vampires are extremely predatory and dangerous, with their major downfall being an aversion to intersecting right angles -- in other words, crosses. But their intelligence makes them valuable tools.
The protagonist is Siri, who is lacking half a human brain. His severe epilepsy led to a neurosurgical operation that removed half his brain and replaced it with technological components. (Siri's father Jim features prominently in Echopraxia).
The world is caught off-guard when a net of alien probes suddenly appears in the sky, then disappears just as suddenly. No communication, and barely a trace left as to their whereabouts. The nations of Earth unite to launch a space mission to investigate this alien contact. The Theseus goes out into the solar system, carrying a vampire commander, 4 primary astronauts and 4 secondaries. Siri is one of the primaries.
While the novel details the journey out to find and explore the source of the alien phenomena, it also flashes back to Siri's interactions with people in his life - his awful mother, long-suffering but frequently-absent father, best friend, and girlfriend. All of these remembered relationships document a struggle with being human. Siri's profession is being a Synthesist, reading the body language and communications of others without ever deeply understanding them. He is mostly passive and doesn't push his opinions on others -- except for the girlfriend, who tried too hard to make him happy.
The mission proceeds and the crew of The Theseus find more than they bargained for. A great First Contact story then unfolds, with some Lovecraftian touches. I don't want to spoil too much, but let's just say these aliens aren't human. The very end of the book points to a future beyond the time setting of Echopraxia, and if you've read that first you know where it's heading.
The vampire in this book is nothing like Valerie in Echopraxia. Where Valerie was really bone-chillingly frightening, Sarasti is merely a threat on the radar. He takes drugs to overcome his aversion to Euclidean geometry, but doesn't put this to any ill use (say, stalking the humans aboard). Now of course the author has clever reasons for the extreme difference in the two vampires' characters, but you'll just have to read the books to learn why.
Blindsight gives a feeling of unease, but not to the level of its successor, and not in the same way. I found the earlier book to be an easier read, although I still didn't always follow everything and found myself rereading a pivotal moment. It's still a richly constructed world that feels dangerously real when you're in the middle of it.
The end of Blindsight has a passel of citations and explanations, as with Echopraxia. I do think the author is, or at least was, pushing an agenda with this book; but at least he's rather transparent about it.
Recommended for science fiction fans and for horror fans who can be a little patient to get to the good stuff.