I make both obvious and subtle references in the first Emerson novel to my two favorite television shows: Lost and Dexter. In general, my barometer for "Is this a good character?" is "Would this character work well on Lost?" I've always felt that Emerson would (I bet she and Kate would have had plenty to talk about!), although ironically, one of my favorite characters ever (from both book and screen) is Dexter Morgan, and he'd be a horrible addition to that crazy island. Had he been let loose on that island, there's a good chance we'd have barely gotten to know Sawyer, Sayid, and Ben Linus!
I've been re-reading a lot of the Dexter books (yes, Dexter was a book character first, and Jeff Lindsay writes him brilliantly) because while he and Emerson share one major characteristic--they both kill people who are typically seen as "bad guys"--they're very, very different. Emerson feels very little compulsion to do this; with Dexter, it's pretty much in his blood. Emerson does it for logical reasons--mainly money, sometimes revenge, and also because she's eventually blackmailed into it--and Dexter, for the most part, does it because killing's what he does, because his Dark Passenger compels him to.
Somehow, reading something that constantly helps me see what Emerson is not is also helping me understand even better what and who she is.