I have to agree with a lot of the others' viewpoints on this. As time has gone by in the SB series I find myself disliking Kayli more and more. I actually read the SB series first (from the first book all the way through the last one, before I ever even cracked open the Ghost Bird series) so I never even thought to compare her to Sang initially. And I actually really liked Kayli in the beginning, I'm all for sassy, strong, opinionated heroines. She'd obviously been through a rough childhood, and basically raised her brother herself, having to abandon her own childhood in order to care for him and her alcoholic father. So, I understood her rough, sometimes abrasive personality as the defense and coping mechanism it is. She's smart, both book-wise and street-wise so as the series progressed, I really expected more....more something from her. I thought she'd step up to the plate and start handling things, but instead it seems development-wise she's gone backwards. What happened to that whip-smart, street-wise girl? It's like she disappeared. She acts rashly, impulsively without thinking through any of the potential consequences--not for herself, or the guys. I know some of the situations she got herself into didn't give her time to think, but some of them she had plenty of time to think through her options, but just doesn't.
Also, she has a tendency to be an annoyingly giant hypocrite about certain things. She demands the guys' secrets while refusing to give up her own (and she definitely has some whoppers). She demands their trust, but won't give hers, because of what? Their criminal backgrounds? If anything I would have thought that would make her closer to them considering her own shady criminal dealings. You'd think she'd know not to judge a book by its cover, considering she's exactly like them! It's only by sheer luck and the Academy guys' intervention that she didn't have criminal charges herself. She's distrustful of the Academy, okay, I can understand her being leery of some secret organization she doesn't know anything about. And the SB Academy guys haven't eased her into it or supported her as well as Sang's Academy guys did. So, yeah I get that. But by this point in the series, after all she's gone through with them, she should trust her Academy guys more. They've always tried to be there for her, and clearly care for her and are concerned about her well-being. So she should trust them, and by extension, should at least give the Academy the benefit of the doubt considering her guys are members, and she knows and loves them.
When we see her at Camp in First Kiss, I wanted to slap her. She was being an unreasonable idiot, coming off like a spoiled brat more than anything. I understand her ambiguous feelings about the Academy, but she doesn't even give it a try or the benefit of the doubt for the sake of her guys (who she's supposed to care for). She's just so close-minded. She's got this idea in her head about what the Academy is, and she stubbornly clings to it no matter what anyone says. Or at least, that was my impression.
Unlike some of the others, I actually like Blake. He genuinely cares about and is concerned for Kayli. I think he would have been great in the Academy if they'd gotten to him when he was younger. As it is, he's kind of a loner and I don't see him submitting to Academy authority now. I do get why Kayli trusts him more, though. It's because she knows he's a loner (besides Doyle), and he's not part of any shadowy organization, that's why she's more willing to accept his word at face value (though a street-smart girl like her should know better than that). Even though I understand it, I don't like it and find it extremely annoying the way she constantly mistrusts Axel, Raven, Corey, Brandon and Marc---who only have her best interests at heart, which you'd think she'd figure out by now! I understand why she wouldn't trust them in the first two books, but we're 4 books in already! So annoying.
Overall, I'll probably continue to read the SB series---despite Kayli, not because of her---I really like the SB Academy gang (Axel, Raven, Corey, Brandon, Marc--and even Blake) and I'll read that series to find out what happens to them, not Kayli unless she undergoes some major character development. I don't want her to be another Sang, she's her own person, but I would like her to be the smart, sassy Kayli we saw in book 1.