The Lives of the Mayfair Witches is a trilogy of books written by Anne Rice, author of The Vampire Chronicles. The series centers around an old family of witches — the Mayfairs — and their involvement with a spirit called Lasher. The books are:
Clap Your Hands If You Believe: The scope and power of most Mayfair's psychic abilities is directly affected by their willingness to accept that they have them. Extremely powerful Mayfair's like Julien and and Rowen are simply so strong that only willful denial keeps them in check. Once Rowan accepts that the deaths she's caused were not just coincidences, she is able to kill at will. In a fit of rage when Lasher was gloating about having killed one of Julien's lovers, Julien truly focused his will and was able to both see and directly attack Lasher for the first time. Most other Mayfair's are superficially aware that they have latent powers, but doubt them and instances in which they manifest. Lasher encourages this, as a huge family of psychic witches would be way beyond his control. Thus most Mayfair's treat the family history as peculiar legends or believe that only certain members of the family had real powers.
Deal with the Devil: Lasher offered the Mayfair family wealth and power if they helped give him a new physical form.
Death by Childbirth: Most women suffer this after sleeping with a male Taltos. When Lasher attempts to create more of his race by raping other members of Rowan's familiy, they all miscarry and hemorrhage. Only Rowan survives, but she has to have a hysterectomy afterwards.
Despair Event Horizon: Ashlar after his decision to convert his people to Christianity led to them being mostly wiped out. Summed up thusly:
At that moment I wanted no more of life. I wanted no more of suffering ordeath, or of the best of intentions resulting in abominable ruin.
Heroic BSOD: Michael goes into a depression after Rowan leaves with Lasher, and it takes Mona sleeping with him to snap him out of it. Rowan goes into one of these between Lasher and Taltos after killing and burying Emaleth, her daughter by Lasher.
Hollywood Heart Attack: When Stuart pulls a gun on them, Rowan uses her powers to make him have a heart attack, and has unintentionally caused similar incidents to happen to several other people during the course of her life.
I Just Want to Be Normal: Lasher cultivates this attitude in most Mayfair's, since he wants to use them in his breeding program, but not have them running around in full control of their psychic powers. A majority of the prefer being just wealthy high society types and have no desire to be witches or deal with the supernatural.
Incest Is Relative: The Mayfairs. Even Michael turns out to be descended from Julien by one of the maids.
When Rowan and Michael come back from meeting with Ashlar, Morrigan smells his scent on them, recognizes it as another Taltos, and goes nuts. When Ashlar comes to visit, wondering why they haven't called, they scent each other, and end up running off together.
Mona (and later Mary Jane) can also pick up Lasher's scent, leading the former to realize he's been attacking the Mayfair women (and nearly got her.)
Most Mayfairs possess at least some degree of Telepathy, which usually includes the ability to sense and communicate with spirits. The more powerful ones also have various Mind over Matter abilities, including telekinesis, pyrokinesis, psychic healing and (in Rowan's case) the ability to kill people with her mind.
Michael temporarily has psychometry after he nearly drowns, but quickly gets annoyed by people asking him to touch things. He loses this ability when Lasher tries to kill him.
Taltos, vampires and some witches have Aura Vision. Witches, especially the Mayfairs, are easily recognized by the Taltos and vampires because to their eyes they appear to glow with a brightness relative to their potential power.
Rapid Aging: A newborn Taltos grows to the size of an adult in a matter of hours.
Reincarnation: Stuart Gordon believed that Tessa was remembering things from past lives, not considering the possibility that she saw them first hand.
Tangled Family Tree: Cousins having sex is the low water mark in this series. It gets a lot more hardcore. Julian alone manages to impregnate his sister, cousins and some of his children.
Mona Mayfair: Michael, for chrissakes, if there is a crime of statutory rape in this state (Louisiana), you'd have to get a lawyer to look it up to be sure. The age of consent between cousins is probably ten, and there may even be a special law on the books lowering the age to eight for Mayfairs.
Teen Pregnancy: Mona ends up pregnant by Michael, and gives birth to a Taltos daughter that she names Morrigan.
Witch Species: Never outright stated that they're wholly distinct from humans. Considering they're genetically-compatible with Taltos, they must be at least a different sub-species.