Alistair is a colonel of one of the world's most powerful army. He's a hero that residents of his country hold in reverence. His actions in the last war brought his country victory and glory, and all these are things he regrets. The war was a crusade against people who didn't believe in his religion, and out of all the soldiers, Alistair had the highest kill count. He now deeply regrets his actions and is searching for redemption by preventing the next crusade.
He's rather emotionally distant, not by choice, but because he genuinly can't express his emotions correctly and finds difficulty empathising with his soldiers, though he wants to. Alistair is cold, a bit quiet, but remains a man of ideals and optimism. He sees the best in people, to a fault. He's a man of incredible focus, tuning out everything but his goals, and a man of quiet, yet poweful, determination.
We don't have a particular voice in mind, but we want to hear yours! Though it should be noted that Alistair is 24. Besides the above lines, we also have an audition script, which you can get here: http://studio-freedom.deviantart.com/journal/Rai-and-Alistair-audition-script-610215127