Destiny's Children (Coalescent, Exultant, and Transcendent, 3 Volume Set)

Baxter first of his Destiny's Children trilogy. In the present, George Poole discovers that he has a twin sister who belongs to a mysterious, ancient quasi-religious order in Rome; in crumbling post-Roman Britain, Regina, founder of the order, longs to recapture the days of her girlhood, when she lived a life of stability and privilege. In alternating chapters, George and Regina each make their way to Rome. George meets his sister and begins to learn something of the order that took her in; Regina-complex, bitter, obsessive-crafts the order that lasts to George's day. Regina digs under the streets of Rome into catacombs for secure living space. George, distantly related to Regina, feels the familial pull of the women still living in the warrens underground, but when he befriends a young, pregnant member of the order, he realizes that they have evolved into a new life form, a coalescent one comprising drones working within a decentralized social order. Book 2 - set long after the events recounted in 2003's Coalescent. When navy pilot Pirius and his crew violate protocol during a skirmish with the alien Xeelee and end up capturing a ship from "mankind's most ancient and most powerful foe," instead of accolades, two versions of PiriusPirius Red and Pirius Blue, from different time lanesreceive punishment. Pirius Red accompanies the eccentric Nilis (we know he's odd because he never wears shoes) to the Earth system to research the captured ship and concoct a way to end the war, while Pirius Blue is sent in disgrace to the Xeelee front for army combat training. As Pirius Red explores the solar system, picking up clues to create a strategy to defeat the Xeelee by striking at their home system, Pirius Blue narrowly escapes death in combat and grows into a leader. Both come to question the doctrines that guide their lives as they realize the extent of their military conditioning. Book 3 -