Fire Upon the Deep, by Vernor Vinge is one of the most wonderfully complex science fiction novels I've read in recent memory. No doubt about it; it's a brick. My paperback had nearly 700 pages! So there's plenty of room for complexity. But don't get me wrong, it's not dull - quite the contrary!
The action takes place over billions of light-years on several different planets and systems and we meet the most wonderfully weird aliens. Normally in a SF novel, we're lucky if we meet one alien different to humans, but Vinge's imagination seems limitless. We meet plenty of humanoids or rather people descended from Human stock. But we also meet bug people, seaweed/tree people, evil butterfly people, people with ivory for leg appendages and several glimpses at even more - ah the possibilities. Most interesting are the Skroderiders (the tree people) and the "Tines", who play a central roll in the action and narrative. They have the most depth as aliens. The Tines are a collective consciousness. They need at least 3 members (which are like dogs with weird tympana for making and receiving sound (within the human threshold and what they call "mind-sound") to become more than "mindless" animals. They gain intelligence and complex communication skills. And they don't necessarily die if one of the members dies. They "recruit" a new member somehow and carry on, changed slightly but still the same "individual".
The idea is that based on what area of space you are in, there are divisions of how well technology functions and/or can even develop. In the outer-most section of the galaxy, it is even possible for "Powers" or Gods to be born. These are super-intelligences which only flourish for a decade or 2 at most. And the action begins when one of these Powers is born - but it is malevolent. It wasn't to take over all lesser beings as extensions of itself. They call it the Blight. Before the Blight was fully manifested one ship managed to escape the research planet that released it. A family of four and most of the children from the planet. They flew to the Bottom, almost to the Slow Zone, where faster than light travel doesn't exist. They crash land on the planet of the Tines and are brutally attacked. The 2 adults are killed and the two children are captured by opposing factions and they don't know the other is still alive. Thus begins a mad race to rescue the children without alerting the Blight, because they believe a counter-measure was transported with the ship. Something that would save the Universe from mindless servitude.
This is a fantastic romp, which will hold your attention from beginning to end. Coming from me, someone who doesn't do well with the really hard SF, that's saying a lot. The ideas are complex, and if you want to understand the concepts you can, and if you don't it's not a big deal! From what I understand A Deepness in the Sky, by Vinge, is a prequel. The events in that novel take place before A Fire Upon the Deep, but was written afterwards.
Highly recommended!
DivaDiane