Trekking through the forest wears on armor. There's mud, twig, bugs, and who knows what else tat gets on it, and a defender must have finely polished armor, clean enough to eat off of, metaphorically speaking, of course, and so, Trenton has taken a moment to do just that, sharing some idle chatter with his bard companion, Caleb.
Naturally, a bard is gonna sing, and Caleb happily does so, mostly relaxing songs to sooth a weary soul after a long day of travel, though when the songs change to more tender serenades, Trenton can't help but feel as if there is a certain 'aim' to them at that point.
"C-caleb... Could you... Ah... Perhaps a different song is in order? How about the one about the wolves, or that battle march, hm? No...?"
Of course not. The bard chooses the song, and sometimes it's the one that he knows will make a certain bird blush.

Trenton © Me, AKA  Zhao
Caleb and art ©  Kokuhane
Coloring by  frostbiteposters

So, the idea behind the coloring:
Given Trenton's past, though he is typically light and cheery, he still has a bit of a dark disposition. There's been a lot of damage done, and a lot taken from him. It has his mind constantly working into those dark corners that are not easy to escape. So, his side is darker. The sun is setting, and night is beginning, and everything will soon be encased in shadows, so his half is darker.

Caleb, on the other hand, is bright and cheery, and knows just what to do to pull Trenton out of that slump once he's in it, and no matter what, Trenton's mood brightens when the husky is around. Granted, they're not together, when Caleb is around, it is still like a brand new day, and the sun has risen to get rid of the gloom and shadows. Needless to say: Caleb is a ray of sunshine in Trenton's world, and the big, blue bird couldn't ask for more.