I found this author by reading the EB series first, OP next, AP after that and still HAVEN'T read any of the KT stories. (What can I say? I've been side tracked by the DE/VGM series instead.)
However, there are fairly consistent themes running through the ones I have read - early abuse in childhood, often of an extreme sexual, mental, and physical nature. (The forced cannibalism in OP1 did squick me out just a bit!)
One of the main things I found interesting about this was how the characters responded - they all became murderous. The Zachs in AP & OP 'killed off' the emotional content of their memories' ability to harm and disturb them, while Eve actually did kill her mother and the others involved. Since these incidents occurred in an 'Author Lord Universe' (i.e. NOT REAL) this is probably as mature of a result as could be expected from people as young as these ones are supposed to be. I am sure that IRL there are many who wish this option were open to them.
The next interesting thing was the characters resulting hyper-sexuality (ITRW this is often an actual response to these types of abuse, so kudos to Mr. Powers for 'keeping it real', so to speak.) and the way they chose to handle it. AP Zach becomes a bit of a hound dog, eventually falling into the start of a pattern of perpetuating abuse himself in AP3 but Kaitlyn has apparently put the kibosh on that though and it looks like things will improve in the hopefully soon-to-be upcoming AP4. Eve removed her physical desires and usual sexually inappropriate responses by becoming a vampire, which will now force her into finding other ways to deal with people and especially men, leaving OP Zach, now an acknowledged Greater Demon, to spend a lot of time making deals for sex without actually seeming to have a bunch of it - though the scene with Keely in OP3 was quite tender right up until he killed her. It left me with the over-all feeling that they were Working On Their Issues and that Things Are Looking Up.
I do plan on hitting the KT books soon-ish because I've enjoyed the other series so much, though since I understand they are Young Adult oriented I haven't exactly been rushing to pull them off the shelf. I dealt with too much teenage angst and too many vindictive cheerleaders when I was in school to be in a hurry to go through all that again...
I also would like to agree with some of the earlier posters re: sex scenes. I feel that sex and sex scenes - even explicit ones - are perfectly acceptable parts of a writer's tools. They can move a storyline along, add to less obvious plot points, or flesh out an author's world-building. Even Louis L'amour, an American writer of classic westerns, had sex scenes in his books. Barbara Cartland and Agatha Christie, as well - though not much because that would have been vulgar. However I think there is also a flip-side of that. Yes, Virginia. There IS such a thing as too much.
For example, I used to love reading Laurell K. Hamilton's stuff - Anita Blake, Vampire Hunter was one of THE ground-breaking series of its time, with no sex at all for the first 6 books or so - just unrequited attraction. The sexual content gradually ramped up book by book going from deliciously naughty to totally red-hot. Unfortunately in later books, as the sex became more-and-more the storyline became less-and-less. It's now to the point that there is less sex in a porno. (Not to mention more plot!) It finally became too much for me. Where I once had all of her books pre-ordered in hardcover I haven't even bothered to read the last two and the one before that I pirated.
Hmm, looking back over this post I might be going on a bit. Sorry. However, I would be interested in hearing other people's opinions on this. When does 'just enough' become 'too much' for you? Or is it a case of 'too much is not enough'? Please let me know what you think...