Derangements are behaviors that are created when the mind is forced to confront intolerable or conflicting feelings, such as overwhelming terror or profound guilt. When the mind is faced with impressions or emotions that it cannot reconcile, it attempts to ease the inner conflict by stimulating behavior such as megalomania, bulimia or hysteria to provide an outlet for the tension and stress that the conflict generates.
It must be noted that people who are "crazy" are neither funny nor arbitrary in their actions. Insanity is frightening to those who are watching someone rage against unseen presences or hoard rotten meat to feed to the monsters that live next door; even something as harmless sounding as talking to an invisible rabbit can become disturbing to observers. The insane, however, are only responding to a pattern known to them, stimuli that they perceive in their own minds. To their skewed perceptions, what's happening to them is perfectly normal -to them. Your vampire's derangement is there for a reason, whether he's a Malkavian who resided in Bedlam before his Embrace or a Venture who escaped from five months of torture at the hands of an Inquisitor. What stimuli is his insanity inflicting on him, and how he is reacting to what's happening!
Derangements are a challenge to role-play, without question, but a little time and care can result in an experience that is dramatic for all involved.
Obsessive/Compulsive
Vampires with an obsessive or compulsive derangement must determine a set of specific actions or behaviors, as described above, and follow them to the exclusion of all else.
Multiple Personalities
Schizophrenia
Roleplaying this derangement requires careful thought, because the player must determine a general set of behaviors relevant to the trauma that caused the derangement. The hallucinations, bizarre behavior and unseen voices stem from a terrible inner conflict that the individual cannot resolve. The player needs to establish a firm idea of what that conflict is and then rationalize what kind of behavior this conflict will cause. Kindred with this derangement are unpredictable and dangerous.
Paranoia
Kindred who suffer from paranoia have difficulty with social interaction. They are distrustful and suspicious of everyone, even their own blood bound progeny. The slightest hint of suspicious behavior is enough to provoke a frenzy roll. This paranoia may even extend to complex and rigorous feeding practices, to keep "them" from contaminating the vampire's food supply.
Megalomania
Kindred with this derangement constantly struggle to rise to the height of power and influence, by whatever means necessary. In a megalomaniac's view, there are only two classes of people: those who are weaker, and those who do not deserve the power they have and must be made weaker. This belief extends to everyone around the vampire, including members of her own coterie. If a megalomaniacal vampire is presented with the chance to diablerize a more potent Kindred, she will be sorely tempted.
Bulimia
In the case of vampires with this derangement, the need to feed is means of relieving the fear and anxiety endemic to the World of Darkness. A bulimic vampire may feed four or more times a night - gorging herself, burning the blood in pointless -or not so pointless- activity, then starting the cycle again. A vampire with bulimia gets hungry much more quickly then other vampires do.
Hysteria
Manic-Depression
Fugue
Sanguinary Animism
The trauma, guilt or inner conflict that causes this derangement forces the individual to focus nearly all of her attention and energy onto a single repetitive behavior or action. Obsession relates to an individual's desire to control her environment -keeping clean, keeping an area quiet and peaceful, or keeping undesirable individuals from an area, for example. A compulsion is an action or set of actions that an individual is driven to perform to soothe her anxieties; for example, placing objects in an exact order, or feeding from a mortal in a precise, ritualistic fashion that is never allowed to vary. If a vampire is prevented from adhering to her derangement, she automatically frenzies.
The trauma that spawns this derangement fractures the victim's personality into one or more additional personas, allowing the victim to deny her trauma or any actions the trauma causes by placing the blame on "someone else." Each personality is created to respond to certain emotional stimuli -an abused person might develop a tough-as-nails survivor personality, create a "protector," or even become a murderer in order to deny the abuse she is suffering. In most cases none of the personalities is aware of the others, and they come and go through the victim's mind in response to specific situations or conditions.
Conflicting, unresolveable sets of feelings and impulses can cause a victim to develop schizophrenia, which manifests as a withdrawal from reality, violent changes in behavior, and hallucinations. This is the classical sort of derangement, causing victims to talk to walls, imagine themselves to be the King of Siam, or receive instructions from their pets telling them to murder people.
The victim of paranoia believes that her misery and insecurities stem from external persecution and hostility. Paranoids obsess about their persecution complexes, often creating vast and intricate conspiracy theories to explain who is tormenting them and why. Anyone or anything perceived to be "one of them" is often subjected to violence.
Individuals with this derangement are obsessed with accumulating power and wealth, salving their insecurities by becoming the most potent individuals in their environment. Such individuals are invariably arrogant and supremely sure of their abilities, convinced of their own inherent superiority. The means of achieving their status can take many forms, from devious conspiracies to outright brutality. Any individual of equal or higher status than the victim is perceived to be "competition."
Individuals with bulimia assuage their guilt and insecurity by indulging in activities that comfort them -in this case, consuming food. A bulimic will eat tremendous amounts of food when subjected to stress, then empty their stomach through drastic measures so she can eat still more.
A person in the grip of hysteria is unable to control her emotions, suffering severe mood swings and violent fits when subjected to stress or anxiety. Hysterical Kindred must make frenzy checks whenever subjected to stress or pressure.
Manic-depressives suffer from severe mood swings, sometimes resulting from severe trauma or anxiety. Victims may be upbeat and confident one moment, then uncontrollably lethargic and pessimistic the next. Kindred with this derangement are constantly on a hair trigger, never knowing when the next mood swing will strike.
Victims suffering from fugue experience "blackouts" and loss of memory. When subjected to stress, the individual begins a specific, rigid set of behaviors to remove the stressful symptoms. This differs from multiple personalities, as the individual in that grip of a fugue has no separate personality, but is on a form of "autopilot" similar to sleepwalking.
This derangement is unique to the Kindred, a response to vampires' deep-seated guilt regarding the act of feeding on the blood of mortals. Kindred with this derangement believe that they do not merely consume victims' blood, but their souls as well, which are then made a part of the vampires' consciousness. In the hours after feeding, the vampire hears the voices of her victim inside her head and feels a tirade of "memories" from the victim's mind -all created by the vampire's subconscious. In extreme cases, this sense of possession can drive a Kindred to carry out actions on behalf of her victim. Obviously, diablerie would be unwise for an animist to perform.