Sentinel Shield is a Royal Guard.
This title comes with prestige, with respect! Those who have it wear it proud!
However, Sentinel isn't an ideal guard. He is sloppy and can be a bit brash. Some wonder how he even got on the guard.
Celestia sees this and thinks he just needs a chance to prove himself, what better chance than escorting her prized pupil Twilight Sparkle in Ponyville to ease her nerves of Nightmare Moon returning.
However, little did she or anypony know. Not only would Sentinel have to keep Twilight safe when Nightmare Moon does return, but his life would change forever.