I think this is without a doubt my favourite picture of yours. The horse is just so full of WIN and I love the knight's expression. He looks like he's just about to stop and ask some peasant which way the baddie went. I love it!
Oddly enough the grays and browns on the knight make him fade into the background as much as the rolling hills. It is his creature who holds the interest of the reader. Firstly the darkness of the creature is starkly contrasted with the background. Secondly, by looking straight at the viewer, the creature seems stronger and more animated than the knight that he is carrying. There seems to be a spark of mischeif and pride in the creature which is not present in his master. Evil the steed may be, by he's also stealing all of the attention due to the master.
I do love this piece. The colors are well balanced, and the landscape just rolls away around these two. The expression on the knight speaks of a gentle interest in things. I imagine that he takes quite good care of his beast, although the grass stains on his armor suggest that he could spend some time with steel polish, and it would not go amiss.