Understated Guardian King

Cole Slade served in special forces under the codename Reaper. His comrade Alexander died and left him one request, to look after Alexander's younger sister Victoria, so Cole took a job as a security guard and said nothing about who he was. On Victoria's wedding day the groom leaves, the guests do not show, and a corporate plot that had been arranged well in advance becomes visible. Victoria, cornered and proud, forces Cole into a fake marriage. That makes them allies, unwillingly, against Tristan, who wants the Kingsley family's tech empire for himself. Cole's old instincts come back. There is a bloody fight in the church, and later there are shows of force at high society banquets. Tristan comes after them for it. They also learn that Victoria's uncle Conrad is the one behind the plan.