He's really changed a lot through the series. There's a lot of character development that I find really really awesome. (Sorry, so I'm a gifted and talented student, which makes me a bit...well I have a tendency to pull apart stories and find symbolism and development and stuff)
In book 1, he's really rough and tough, and is constantly swearing. Thank you Mrs Alvarez, for making up the swear words. It makes it easier on my heart. :)
In book 2, he's always angry, and still rough and tough despite everything. He's in complete denial.
But in book 3, we suddenly see a nicer side of him. And he has more self control, and doesn't swear. I suddenly can see him as the kind of guy who's the sun to his younger brother. Sidenote - Brauk is the sun to Rahkki (I think that's from ROTR #1) and Tuni called Rahkki, Sunchaser, the moon.
So if anyone wants to join in on my symbolism and character development ramble, you're most welcome. ;)