Voldemort's revival ritual is actually a corrupted blood adoption ritual. With Harry being the last Potter and Voldemort not really knowing what family magic allows people to do, we end up with Harry now having command over Voldemort like a child if he prefaces any command with Voldemort's full name (ie. "Tom Marvolo Riddle, put your wand away and sit on your hands!"). Meanwhile all the Death Eaters are by proxy bound to Harry as well so it works on all of them too.