With a snap

This power might sound simple enough I snap my fingers and whoever I want is a slave to my will however there are some parameters to this power. First, I need to make sure the snap is pointed directly at the person, the second they need to see my fingers when I snap what happens after that is they will go in a trance and I can give them orders, and Finally, I can only do it to one person at a time other then that comes the real question who is the person who has these powers