Was Traitor's Blood your first novel?

First full novel, yes. I had one failed (and awful) attempt back when I was about twenty, but I don't count that! The subsequent novels, Devil’s Charge and Hunter’s Rage, continued Stryker’s story, picking up where Traitor’s Blood left off, and the fourth instalment, Assassin’s Reign, will see him become embroiled in the Siege of Gloucester.