Knights of Equestria

My theory on royal guards (and why they all look alike) is that when they enlist they swear their obedience to one of the princesses. Those that swear to Celestia become the Day Guards, and the ones that do to Luna become the Night Guards. When they do, they get part of the Princess' power when they are "knighted" which changes their looks. Day Guards all become white coated with blue manes, and Night Guards get gray coats with yellow slit eyes and fuzzy ears. And if they are pegasus, their wings turn into bat wings.