Shrine of Stars — Paul McAuley

Who would lay time to rest, or raise it up from its tomb?
The Ancients of Days - humans returned from a long exile in the depths of time and space and history - brought heresy and doubt to the artificial world of Confluence, and ignited a terrible civil war, of all the varied creatures of Confluence's ten thousand genetically manipulated bloodlines, only young Yama holds the power to end the conflict, for who ever controls him controls the myriad machines of the world. Though now a helpless captive being forged intoa weapon of horrific consequence, Yama must win the struggle to reclaim his soul, and complete his search for the true story of his origin - a story mapped eons before his birth.