The Red Court of Vampires are less human-like than the White Court. Instead they are slimy bat-like creatures hidden behind incredibly sensuous human costumes (made of an outer skin). It is revealed in Changes that the oldest and most powerful red court vampires are capable of wearing any flesh mask (that is, turn into any human), and that their flesh masks can fully protect them from the sun, so that they can walk about in broad daylight. They use these costumes to trick their prey into being more comfortable and to hide in plain sight. They are incredibly strong and fast, and can shake off any injury quickly. The Red Court is vulnerable to sunlight and to having their bellies cut open, which can spill the blood they have drunk and eventually kill them. Their saliva contains a potent magical narcotic which gives the prey a euphoric feeling and is highly addictive, allowing the Red Court to control their victims rather easily. The narcotic lowers the victim’s inhibitions while dulling the pain of the vampire’s bite. Addicted humans have been shown to go to great lengths to protect their vampiric masters, and willingly provide information from the mortal community as needed.
The Red Court is also capable of transforming ordinary humans into vampires in a two-step process: the human is first infected with the vampiric thirst for blood (gaining supernatural speed, strength and endurance in the process) and then completes the change into the demonic form upon killing a human victim in their first feeding. Infected humans with sufficient strength of will have been known to refrain from feeding for an indefinite length of time (magical bonds, regular exposure to sunlight, and avoiding physical intimacy all help), but no cure has yet been found for the “half-vampire” infected state. It is intimated that the Faerie Queen Mothers, or a being of similar power, could cure, or rather completely destroy, the vampiric infection with a magic known as an Unraveling (see Summer Knight). Their hunger for blood makes controlling their emotions very difficult, and when in a situation where emotions run high (such as during a fight or when engaged in physical intimacy), it is much easier for them to lose control.
The Red Court is highly organized in a feudalistic system with a King at the top, followed by Dukes and other ranks. The Red Court began a war against the White Council in response to Harry’s actions in Grave Peril, and the war is a long-running plot thread, continuing through subsequent books with the White Council on the defensive and struggling against the Red Court and their allies, while being assisted only by a few smaller allied organizations and reluctant help from the Faerie world.
In the events described in White Night, the White Court of Vampires, headed by Lara Raith and her figurehead father, the King of the White Court, urged that there be a peace between Wizards and Vampires. In Turn Coat, it is confirmed that the Vampire Courts are just “catching their breath” in order to attack again. Also in Turn Coat, it is stated that the Red King is an incredibly powerful vampire who has lived nearly four thousand years.