I must disagree with that opinion. While yes, Amicus can be somewhat "dumb" as you said, that's the point. He was the spoiled son of the late emperor and obvious candidate to take the throne being Virginia a female who can't be in a position of power and Cassius having that illness, Amicus had not many struggles in his life to make him act any different way but he was never incapable or a complete idiot like Alex. On Marcus side...well, I do not seem to see why he would be naive, he did all he could to stay alive in an unlikely situation. He waited for his wolf to resolve most of the situations, but only because he was waaaay out of his league having to trust him to bring him back home and he actually never waited to things to be solved on its own, once the cat was out of the bag he went and saved Amicus. Marco's evolution is interesting cause he went to be de dumb silent pet to be will around the palace as it was his own (and probably will be his palace in the future). So yeah, they may have flaws, but I don't think it of bad writing. On the contrary, nothing seems forced or "out of the blue". Even the "lack of character" from Cato was well thought, he wanted to have control to lead the wolves on another war against Khemia, so he would not have the "Tail-raiser son of the former emperor" ruin everything just because he fell in love with a monkey. To resume, they have flaws because they are not perfect and they grow along with the story. They will never be perfect and that is what makes it to be even more believable.