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 Series in chronological order (novels & anthologies only)
Bitten (narrator: Elena)
Stolen (narrator: Elena)
Dime Store Magic (narrator: Paige)
Industrial Magic (narrator: Paige)
Haunted (narrator: Eve)
Chaotic (novella in "Dates from Hell", narrator: Hope)
Broken (narrator: Elena)
No Humans Involved (narrator: Jaime)
Twilight (story in "Many Bloody Returns", narrator: Cassandra)
Stalked (story in "My Big Fat Supernatural Honeymoon", narrator: Clay)
Personal Demon (coming Apr 08, narrators: Hope & Lucas)
 Series in chronological order (online fiction included)
Here's the list with the online fiction included. This does not mean the stories are intended to be read in this order!  The online fiction was written after the novels, so they don't include anything that is essential for understanding the novels.  They're simply "extras," dramatizing events mentioned in the novels.
If you've read the books, you can browse the online fiction, picking the stories and narrators that interest you.
Rebirth (online story, narrator: Aaron)
Infusion (online story, narrator: Malcolm)
Demonology (online story, narrator: Talia)
Birthright (online story, narrator: Logan)
The Case of the Half-Demon Spy (online story, narrator: Adam)
Expectations (online story, narrator: Lucas)
Truth and Consequences (short story, narrator: partly Elena)
Territorial (online story, narrator: Karl)
Bitten (novel, narrator: Elena)
Ghosts (online story, narrator: Jeremy)
Escape (online story, narrator: Eve)
Stolen (novel, narrator: Elena)
Dime Store Magic (novel, narrator: Paige)
Industrial Magic (novel, narrator: Paige)
Wedding Bell Hell (online story, narrator: Paige)
Haunted (novel, narrator: Eve)
Adventurer (online story, narrator: Kenneth)
Chaotic (novella in "Dates from Hell", narrator: Hope)
Bargain (online story, narrator: Xavier)
Broken (novel, narrator: Elena)
No Humans Involved (narrator: Jaime)
Framed (online novella, narrator: Nick)
Twilight (story in "Many Bloody Returns", narrator: Cassandra)
Stalked (story in "My Big Fat Supernatural Honeymoon", narrator: Clay)
Personal Demon (coming Apr 08, narrators: Hope & Lucas)

 Can a reader skip books?
Short answer? Yes.
Long answer...
People ask me whether they can jump right to the witch books, or skip from Stolen to Broken.  Yes, they can.  The books are written so you can (I hope) pick it up anywhere and not be totally confused.  Mildly confused, feeling like you've missed something?  Yes.  But you can follow the story.
Although the narrator changes, the books take place in chronological order, in the same universe with the same cast of characters.  A narrator from one book will appear as a character in another.  Events from one book will be referenced in others.  Some subplots carry on from novel to novel, bridging narrators.
For example, if a reader skipped from Stolen to Broken, a character named Jaime will join the Pack in Toronto, and the reader will be wondering "what's a necromancer, who is this woman and why is she acting so oddly around Jeremy?"  Eventually it'll become clear and, at no time, should that missing knowledge affect a reader's understanding of the main plot.
 Why does the narrator change?
I never intended Bitten to be the beginning of a series. It was conceived as a stand-alone book, with all the major plot questions resolved. After the book sold, the question of a sequel arose. My reaction was honestly ambivalent.  As much as I enjoyed the werewolves, I feared that writing a second Elena book would mean locking myself into an Elena series.  It wouldn't take long before I'd start losing steam, eager to try something else.
I decided to write a sequel that I hoped could indeed launch a series, but not a series strictly about werewolves.  I introduced other supernatural "races" and a character who took over narration of book 3.
For me, then, changing narrators isn't a marketing ploy—I'm told repeatedly that I'd sell better if I didn't!  Instead, it's all about keeping it fresh and challenging, which is very important to me as a writer.  I love what I do, and I don't ever want to lose that.
The narrators may change, but the cast of characters doesn't diminish.  If you liked a narrator, she's certain to return as a secondary character and—if enough readers liked her—as the narrator of a future book.