Disquiet Gods: The Sun Eater (Book Six) by Christopher Ruocchio

"Disquiet Gods," the sixth book in Christopher Ruocchio's Sun Eater series, continues the saga of Hadrian Marlowe, a legendary hero in a galaxy beset by war and divine threats. Nearly two centuries have passed since Hadrian withdrew from his imperial duties, choosing exile on the desert planet Jadd with his daughter, Cassandra. However, the persistent conflict with the Cielcin and the emergence of a devastating plague compel him to return. The Sollan Emperor's secretive agency, HAPSIS, has identified a formidable Watcher—a god-like entity worshipped by the Pale Cielcin—and enlists Hadrian's aid to eliminate this existential threat. Reluctantly drawn back into the fray, Hadrian, accompanied by Cassandra, embarks on a perilous mission that intertwines personal stakes with the fate of the galaxy.