 Stross was hesitant, but gave it a shot.He wanted to be original but not "too original" and create something hard to market.He decided his series would be his own spin on both the works of Roger Zelazny's "The Chronicles of Amber", which featured a hero with special world-travelling powers, as well as the "Paratime" works of H. Beam Piper, which features an organization with the power to basically raid and exploit multiple alternate histories.