Merrick (originally spelled 'Merrique') is the daughter of Cold Sandra, who in turn is the granddaughter of Great Nananne. Her older sister was Honey in the Sunshine, who died along with their mother in a murder/drowning. Found with Cold Sandra and Honey in the Sunshine was a watch given to Cold Sandra from their Oncle Vervain, who told Merrick that it did not tick for her; therefore, there was no need for her to have it.

It is revealed later in the book that Oncle Vervain knew time would stop for Merrick because she would become a vampire.

This branch of the Mayfairs, descended from Julien (of course), are witches who practice Vodou alongside Catholicism. They have little or nothing to do with the First Street Mayfairs, and when Merrick took a tour of the First Street house, she did so discreetly, during a holiday tour. When Great Nananne dies, Aaron Lightner has to hide during the funeral, explaining to David Talbot that his work on the Mayfair Witches has made him known to the two Mayfair attorneys who arrive with the interests of the family at large in mind - Ryan and Lauren Mayfair. It is Lauren Mayfair whom Rowan is with when she meets Merrick Mayfair, noting that Merrick does not carry herself with her hips as the center of gravity like most women do.

Merrick is one of the three members of the Talamasca whom Sterling Oliver referred to in BF who were lost to vampirism.

Many of the Vodou Iwa that corresponded best with Catholic saints took on aspects of those saints as Catholicism was enforced among the African slaves. Vodou basically went underground at this time but was never abandoned as the slaves who had brought Vodou over to the U.S. and Haiti from Africa kept it alive.

Vodou Dance

Here is what Wikipedia has to say on the subject of Vodou and Catholicism in Louisiana:

Louisiana Vodou on Wikipedia

Catholicism on Wikipedia

Sacred Arts of Haitian Vodou

Haitian Vodou on Wikipedia

Here is a page on Wikipedia that gives an overview of the Olmec, whose jade mask Merrick recovers from the cave in Central America:

The Olmec on Wikipedia

Olmec Art

Merrick is contacted by David Talbot in his vampiric form on behalf of Louis, who wants to make contact with the child vampire, Claudia, who died in Interview With the Vampire. Louis's guilt over Claudia has not waned over time, and Merrick has recovered Claudia's diary found by Jesse in the wall of the New Orleans townhouse. Upon reading it, she wants reassurance from Louis that contacting Claudia is what he really wants. He says he does.

Claudia's words only confirm the words in the diary. Her words are so harsh that Louis attempts to incinerate himself by laying in the sun. His attempt fails as he does not completely burn. It takes the healing blood of Merrick, David, and finally Lestat, who has roused from his self-imposed sleep, to save Louis.

David Talbot, the narrator of Merrick, spends a great deal of time telling of Merrick's early life; specifically, his role in it. He recounts in particular a trip to Central America, where Merrick recovers an ancient mask from the same cave where her stepfather, Matthew, contracted a fatal illness. David, too, nearly dies, but Merrick is untouched. The mask makes spirits appear as living people. Merrick wants to use this to contact her dead sister, Honey in the Sunshine. Merrick feels as guilty about her sister's death as Louis feels about the loss of Claudia.

Olmec Jaguar

Oncle Vervain's Watch

An exploration of this unique branch of the Mayfair family tree:

Mayfair Relatedness~Merrick Mayfair

Exploring New Orleans Architecture-Le Musée de f.p.c.

Please see What Is a Witch? for more discussion on the religious and spiritual practices of the Mayfair Witches.