I love it! I love the image of his coat being like his armor... and really, if his coat is a bit stained and frayed at the edges, so is his armor so the metaphor worked that way too. And I liked the line about him racing to the next mile marker away from who he used to be. Actually I like each line in this, singly and together (lol)

Is it bad though, that knowing that this is a pairing prompt, immediately upon reading that the coat has stains on it, my mind immediately went to a very bad place? (Hangs head in shame.)

Anyway, really, really good. I like how much characterization you packed into something this short.