Original comic here: http://nimaru.deviantart.com/art/Gathering-Elements-Rook-267204706

Rook, the element of loyalty or, as the author says, the element of "will". Each of the main characters has an unique theme that reflects both their "element" and their actions during the story. First of all, each element is represented by an instrument or group of instruments. In this case, brass instruments: each time Rook appears he can summon the whole brass section! When I was composing the theme for the element of loyalty/will I put a lot of attention in the way the melody moves, if you look closely Rook's theme is always ascending, in fact it's a constant modulation towards an higher key, but at the same time the melody has a steady center, namely the 4 F sharp present in each phrase. The key of D Major is also relevant, being a regal and bold key to me, I see it fitting for a royal guard or such a militaresque figure in general. In this scene the ascending nature of the theme is toned down by the presence of Celestia, with her soft descending phrases, she adds a gentle tone to the main theme together with the playfulness and love given by Rook's family (his son, introduced by the flute, and his wife by the clarinet).

I'm very slow at this, I'm sorry...but that's basically because I suck at photoshop/premiere, I'll try to deliver faster next time...