Dreamfall — Joan D. Vinge

Once, Cat was a pawn; once, he was bait...

Now Cat is a scholar, studying the cloud-whales of Refuge: remarkable aerial beings whose very thoughts fall from the sky to form vast reefs of pure, marketable data. But suddenly, Cat plunges through Refuge's veneer of civility into a nightmare of brutal bigotry aimed at the native Hydrans. For Cat is half-Hydran...and now he must fight to save a love, a heritage, and a power like none he's ever imagined, battling a merciless state that plunders a world's shattered dreams. Only this time Cat's not a pawn. He's not bait.... He's a target.