(from the wikipedia site)
This court is the most humanlike group of vampires. They are succubi and incubi who feed off the emotions and life force of their prey. White Court Vampires can do this in many ways. The Raiths are sexual predators; they use their supernaturally good looks and an energy aura around them to attract both men and women to them. During intercourse, or any contact where emotions like lust are heightened, they feed off their prey. Victims of the feedings of House Raith grow to enjoy the experience and become bonded to their predator like a drug addiction. Other Houses such as House Malvora (with which Thomas's cousin Madrigal is involved) feed off fear. The Skavis feed off despair. The White Court is not endowed with as much physical strength as the Red or Black courts, but they make up for it by having many fewer vulnerabilities. Sunlight and holy artifacts (both of which affect vampires of the other Courts) do not harm them at all. Their power derives from an internal demonic essence they call the "Hunger" which acts like a battery. If they refrain from feeding for too long, the "Hunger" drives them into a frenzy where they must feed (almost always killing their victims), and can drive them permanently insane. When needed, they tap this store of energy to augment their strength, speed, resilience, and healing ability far beyond normal; while doing this, they radiate waves of cold (possibly an illusory reaction of normal humans to their energy sink), their skin whitens, and their eyes turn unnaturally silver. White Court vampire blood is pinkish instead of red. Their largest weakness is true love: people who are, or have recently been, in real, affectionate and sacrificial love are highly resistant to White Court control, and can even physically burn and blister vampire skin. Also, White Court vampires are born, not turned like Red and Black Court vampires; if the offspring of a White Court falls in love with someone that feels the same way before feeding for the first time, the love can destroy the demonic side before it can manifest allowing the person to live a normal, mortal life. Unlike the other courts, the White Court prefers to avoid direct confrontation. They are a court of schemers and prefer to stab each other in the back in exquisitely detailed plots to impress the others in the Court. At the moment Thomas's father is the King of the White Court, but in name only; his sister Lara is in charge, pulling the strings from the background to keep up appearances.