This is one of those books where I wavered for a long time between 3 and 4 stars. Over here, I lay out roughly why I make a decision between those and sticking to that really does make me give Borderline 3 stars rather than 4. My first clue probably should have been that I could put it to one side for a few days and not really wonder about what was going to happen next.
Anyway, on to the plot. Borderline is the first in an urban fantasy series but one which thankfully escapes the sexy leather-clad woman discovers her secret abilities/heritage and that the world isn't quite what everyone thinks. Well, it has the latter but our protagonist has all sorts of issues - a significant mental health issue that's ongoing through the book (and referenced in the title) and also the serious physical aftermath of a failed suicide attempt. Millie is recruited straight from her rehabilitation centre into working for the Arcadia Project, a group of humans who work as intermediaries with the fae, in Hollywood of course!
It's pretty much stated early on that the kind of people that get recruited are those who won't be missed if they disappear and that the attrition rate is high, with Millie subsequently also discovering that the amount of metal she now has holding her skeleton together helps her deal with some fae magic. There's an ongoing plotline about an actor (who is secretly fae) disappearing and the idea that fae and humans are matched together - one of the things I liked about this book was the fact that when Millie meets her fae match, the circumstances mean nothing can happen and nothing does happen, rather than some kind of magical exemption for plot service purposes.
Anyway, the things that annoyed me a little about the book and which mean I probably won't be reading the sequel (Phantom Pains): while I accept that it would be difficult to get across Millie's mental health issues without it, the ongoing monologue about 'I do this because of my brain doing this' got a bit wearing after a while (a.k.a. 'my ongoing issues with first person'). Likewise, I didn't really give a crap about any of the characters sufficiently to wonder about their future lives but then the author also killed off one of the more interesting characters, making me even less likely to continue with it.