Royal Guard Theories.

[20% Cooler Than Cake 161]

"A cutie mark appears on a pony's flank when he or she finds that certain something that makes them different from every other pony." - Cherilee

 

I think that just because the guards have the same coat and armor, it doesn't imply at all that they are the same or even similar to each other when it comes to cutie marks. The reason that they are defending the princesses (or at least trying to) is because their cutie mark has some connection to the job. For example, one guard might have a special talent at helping others. Another might be quick at making decisions, and perhaps another can easily spot intruders. Some may have more unspecific, general talents, such as following as listening to others.

 

As, for their apparently blank expressions, keep in mind that this is just like our armies, and the guards are simply following the orders of their princesses, because that is their job and there isn't really anything else that they should be doing. One more thing is that I don't believe that the majority of these guards' cutie marks have to do specifically with fighting, as their job seems to be more of an intimidation and surveillance duty than violence.

[cider float 2,535]

Bigger question is why most Royal Guards are white or gray. Flash Sentry is the one that stands apart though.

 

Makes me wonder why they made the decision to make Shining Armor white setting him different from his sister and parents just so he would not look different from the Royal Guards. Does Celestia only hire white Royal Guards because she's white?

Edited January 7, 2016 by cider float