DuQuesne, the one thing that's been consistent throughout the books is that Tarrin has never had a very firm grasp on the concept of morality...the way you would define it.
Actually, Tarrin adheres to a very strict code of conduct. What is different here is that his concept of good and evil, right and wrong, proper and improper, is vastly different from what most others see it. And it's probably what makes him so interesting to me.
The biggest aspect of that personality has been and probably always will be, "the end justifies the means."
Does Tarrin have morals? You bet. For instance, he'd never knowingly harm a child. He wouldn't harm a member of his family. He never breaks his word. He does not lie. He never uses his magic without good reason. He honors and obeys his parents and superiors. He is caring, loving, attentive, and compassionate to his friends and family.
But, on the other hand, does he see something immoral about stealing souls? Not really. He certainly doesn't like doing it, and would have found a different way if there was one, but there wasn't. And since it was his only course of action, it immediately becomes an acceptable course of action in his mind. To him, it is a means to an end, and that end is so important that it warrants this kind of extreme action. He wouldn't be doing it if he saw any other way, but in his mind, the objective makes what he is doing acceptable TO HIM.
He must be willing to make the choices that must be made.
Actually, the incident with the sages is a good example of both his morality and his lack of it. He roared into the sage's compound and destroyed it, killed sages, because in his mind they had wronged him, and violence is Tarrin's immediate response to such betrayal. But he also didn't outright kill the lead sage, nor his secretary. He doled out what he saw as just punishment against the sage, and permitted the secretary to live when she earned that right, in his eyes.
Tarrin is only a wanton destroyer when in a rage. Everything else he does, he does it because he has a specific reason for it.
And, as you and others have seen, his duality of mind has evolved simply beyond him being a Were-cat. It is now a fundamental aspect of his basic personality. All those years as a Were-cat has stamped that mode of thinking into him, even without the Cat in his mind.
This fundamental dichotomy, the two sides of him, human and Cat, hero and villain, good and evil, has been a cornerstone of the story for a long time. It makes him what he is, and he wouldn't be half as interesting without it.
Tarrin isn't your usual protagonist DuQuesne. He'd be classified by a literature major as a "dark hero." He is equal measure of hero and villain, a man working towards a noble end, but commiting evil in the course of it. At times in the books, he actually was the valiant crusader, but at other times, he was just as sinister and evil as the bad guys he was fighting against.
It is what he is, and his concept of morality and his outlook on life reflect this duality.