Sable Sword is a guardspony of Canterlot castle. Princess Luna is... well, a princess.
He has a fondness for hooves. She has a fondness for weird experiences. The two don't know each other on an emotional level, and they probably never will. For what reason is she giving him the chance to worship her feet?
You won't know, and I'm too lazy to tell you. She just is.
A lime story involving hoof worship, written as a gift for someone on FA who shall remain anonymous. Rated teen, just to be safe.
...I need to rethink my life.