Rebel Sutra

Aristocracy: literally, "government by the best." On most worlds, with most aristocracies, it's not a word you'd take literally.
On the other hand, there's the colony world of Maya: a difficult and unbalanced place, inadvertently settled long ago by a colonizing spaceship that was headed elsewhere, but broke down and had to settle for Maya instead.
These days Maya is run by the Changed, an inbred elite. From their hillside Xanadu they can look down on the grotty, badly maintained streets of the city of Babelion, and its swarms of merely human colonists.
For generations now, the Changed have been tinkering with their own genetic makeup. On the whole, they're smarter, faster, longer-lived - and acutely aware of their own superiority. What they're not admitting is that they've become a separate species.
Then, one year, Arsen shows up. He's strong, smart, wildly charismatic, politically aware, and he doesn't believe in the superiority of the Changed. Still, he's nothing the system couldn't cope with - until he hooks up with Della, a member of this year's graduating class who's supposed to be tutoring him for the test. Della's born-and-bred Changed, but she's every bit as rebellious as Arsen, and she has a nasty streak of political shrewdness to match Arsen's idealism.
Not that they're talking politics when they're supposed to be studying, not at first. They're a couple of teenagers, doing what unsupervised teenagers do. But what gets started between them will tip the whole power structure of Maya on its side and start it rolling downhill....