Quais são os possíveis efeitos colaterais em um Membro por beber sangue fae?

Bem, depende em grande parte de qual versão você está olhando. As duas verdadeiras definições de poderes estão na Idade das Trevas: Fae (então, supostamente, é para os antagonistas de Vampiros se beneficiarem, não os PCs de Vampiros) e Vampiro: A Idade das Trevas, que mais tarde foi removido na edição revisada (Dark Age: Series).

Dito isto, abaixo estão as referências que eu poderia encontrar nos livros do World of Darkness. Vampire V5 e Vampire Dark Ages V20 não mencionam fae, e eu não tenho a edição Vampire 1st, 2nd ou 3rd para verificá-las.

Idade das Trevas: Vampiro

Rumor ascribes marvelous properties to the blood of werewolves, faeries and other creatures. Experience shows that vampires who try to feed on such targets almost always end up drained of their own blood and therefore unable to report on any special benefits gained. Feeding rules, pg. 164-165.

Faerie blood has strange effects on Cainites who drink it, driving them temporarily (or even permanently) mad. Fae rules, pg. 298.

Vampire the Masquerade: décimo sexto aniversário

Some Kindred (such as the Malkavians, the Ravnos, and the Tremere) hunt faeries for their blood, believing it to be far more potent than mortal blood. Among those who claim to have tasted this sweet vitae, the experience is quite varied. Some claim that fae blood tastes little or no different from mortal blood; others speak of rapturous bliss, hallucinations, or transcendent experiences. Some compare it to feeling the morning sun shining upon one’s face once more — both in its exhilaration and in its excruciating pain. Fae rules, pg. 383.

No mention of Fae on feeding rules.

Idade das Trevas: Fae

Vampires cannot feed on inanimae, as they do not possess blood. A vampire who attempts to feed on a water inanimae recieves only a mouthful of water for her trouble (woe, the, to the vampire who feeds on a fire inanimae). Fae blood of other Origins, however, generates potent effects. All system information given is for changeling blood, and effects last until all faerie blood has been spent. The blood of firstborn is twice as potent as that of changelings, increasing the following effects twofold. For example, changeling Summer blood adds two dice to soak sunlight and fire, while firstborn Summer blood adds four – and firstborn Autumn blood doubles the radius of its negative effect.

• Summer blood adds two dice to soak sunlight and fire, but causes a soft, false sunlight to radiate from the skin, dealing one level of lethal damage per turn to other vampires.
• Spring blood causes drastic mood swings, increasing Charisma by 1 point when in good spirits but raising the difficulty to resist frenzy by +1.
• Autumn blood allows a vampire to read the surface thoughts of others (as Auspex 4), but all thoughts of those within a fifteen-foot radius intrude upon her mind (spend a Willpower point per scene to focus on any specific thoughts).
• Winter blood increases any one Physical Attribute by 1 point, but increases the need for blood so that any blood consumed yields only half the normal blood points.
• Solstice blood has no special effects.

Vampire systems, pg. 181.

Vampiro: A Idade das Trevas A partir de Aleatória's responder.

Drinking the blood of the fae can be a chancy prospect for a vampire, though, because of its potency it is one many are willing to take. Each point of blood taken from a faerie equals two Blood Points. However, any character imbibing fae blood risks certain dangerous side-effects. First, the character risks frenzy. Any vampire who drinks faerie blood must immediately make a Self-Control/Instincts roll (difficulty 4+ the number of Blood Points ingested). Failure indicates that the character is overcome by the heavy rush of the powerful blood, and will seek to gorge himself with blood. The character will not stop drinking until the frenzy has subsided. Even if he has drunk to his capacity, he will continue to drink, though no benefit will be gained by this extra blood.

Assuming the character makes the frenzy roll (or even if she didn't), she must then make a Stamina roll (difficulty 8) to avoid suffering any side-effects. Side-effects are always determined by the Storyteller - they can be chosen randomly or assigned, whichever seems most appropriate. Some possible side effects from drinking faerie blood are:

• The character begins to violently eject blood from the ears, eyes, nose and mouth. All blood consumed is lost, plus an additional 1-10 Blood Points.
• The character suffers violent hallucinations. These hallucinations last for approximately 10 minutes for every Blood Point ingested.
• The character becomes bound to the faerie in question. This has the same effect as a Blood Oath.
• The character falls completely in love with the next person they see (other than the faerie).
• The character immediately enters torpor.
• The character gains one point of Appearance, but loses a point of Perception. These effects are permanent.
• The character gains all the effects of Heightened Senses (see Auspex, page 143), though these senses cannot be turned off. Increase the difficulty for any roll involving Wits by two. This effect last for one hour for each point of blood consumed.
• The character begins to glow with golden light. This light has the same effect as sunlight to any other nearby, though the character is immune to the effects.
• The character will be overcome by emotion, and breaks out into tears of blood every time he hears music. This effect lasts one night for each Blood Point consumed.
• The character can see through all faerie Glamours. This allows a character to see faeries who are invisible and recognize them in their true form. The character had best keep his knowledge secret, lest he angers the faeries - they do not take kindly to having their secrets revealed. This effect lasts one hour per Blood Point consumed.

A versão antiga de Vampire: Dark Ages entra em mais detalhes. A edição 1996 (acredito que seja a primeira edição) na página 259 explica o Fae através dos olhos de vampiro. E a página 262 explica o que acontece quando um vampiro bebe sangue Fae.

Bebendo sangue das fadas

Drinking the blood of the fae can be a chancy prospect for a vampire, though, because of its potency it is one many are willing to take. Each point of blood taken from a faerie equals two Blood Points. However, any character imbibing fae blood risks certain dangerous side-effects. First, the character risks frenzy. Any vampire who drinks faerie blood must immediately make a Self-Control/Instincts roll (difficulty 4+ the number of Blood Points ingested). Failure indicates that the character is overcome by the heavy rush of the powerful blood, and will seek to gorge himself with blood. The character will not stop drinking until the frenzy has subsided. Even if he has drunk to his capacity, he will continue to drink, though no benefit will be gained by this extra blood.

Assuming the character makes the frenzy roll (or even if she didn't), she must then make a Stamina roll (difficulty 8) to avoid suffering any side-effects. Side-effects are always determined by the Storyteller - they can be chosen randomly or assigned, whichever seems most appropriate. Some possible side effects from drinking faerie blood are:

• The character begins to violently eject blood from the ears, eyes, nose and mouth. All blood consumed is lost, plus an additional 1-10 Blood Points.
• The character suffers violent hallucinations. These hallucinations last for approximately 10 minutes for every Blood Point ingested.
• The character becomes bound to the faerie in question. This has the same effect as a Blood Oath.
• The character falls completely in love with the next person they see (other than the faerie).
• The character immediately enters torpor.
• The character gains one point of Appearance, but looses a point of Perception. These effects are permanent.
• The character gains all the effects of Heightened Senses (see Auspex, page 143), though these senses cannot be turned off. Increase the difficulty for any roll involving Wits by two. This effect last for one hour for each point of blood consumed.
• The character begins to glow with golden light. This light has the same effect as sunlight to any other nearby, though the character is immune to the effects.
• The character will be overcome by emotion, and breaks out into tears of blood every time he hears music. This effect lasts one night for each Blood Point consumed.
• The character can see through all faerie Glamours. This allows a character to see faeries who are invisible and recognize them in their true form. The character had best keep his knowledge secret, lest he angers the faeries - they do not take kindly to having their secrets revealed. This effect lasts one hour per Blood Point consumed.