Storyline A Dark-Hunter Christmas:
A Dark-Hunter Christmas (Dark-Hunter #2.6)
This is the special Christmas story that features the gangster Gallagher and Simi when Gallagher is temporarily relocated to New Orleans to help battle Daimons.
Written as a gift for DH fans, it originally appeared in the back of the first edition of Dance with the Devil. It's also found in its entirety in Dark Bites, and you can read the whole thing as an excerpt on the above link by clicking "Read the Whole Story Here".