Harrison Gray #1 Fan

Keep in mind Kit isn't just mad at Ty — they are mad at each other! That said, I don't think Kit is ever really "over it" at the end of Queen of Air and Darkness. He's just in a different emotional place than he was earlier in the book.

What might look like "being less resentful" is in part resignation. Kit is to some extent resigned at the end of QoAaD; he leaves believing that's probably the end of his and Ty's story. He'll miss Ty, eventually he'll stop missing him so much, and life will move on.

The problem is... it doesn't.

His feelings for Ty don't get smaller. They don't fade into the background the way he imagined they would. So the hurt doesn't disappear either. If anything, there's something especially painful about realizing that time isn't fixing what you thought time would fix, and that doesn't make Kit less angry in the end, it makes him more angry.

So I wouldn't say Kit's anger disappeared and then came back. I'd say the hurt never really went away. As he realizes that Ty still matters to him just as much as he always did, it's only natural that some of those feelings would, as you said, "redirect some of his insecurity and hurt into anger." Love and anger are often much closer together than we'd like to admit, given that they are both intense feelings. If he'd forgiven and forgotten Ty there wouldn't be much coming back from that — he'd just be indifferent to him.

And it's not that he's just mad about being hurt. He's mad because what Ty did put Ty in terrible danger, Kit was warned about that, and he's furious that Ty didn't care about his own life as much as Kit did. I'll give you a little of what Kit thinks himself in TWP:

THIS MAN IS SO FINE. I'M SO DOWN BAD FOR HIM AAAAAAAAAAAA