Strigoi

''“No man knows till he experiences it, what it is like to feel his own life-blood drawn away into the woman he loves.” ''― Bram Stoker, Dracula

Rare and dangerous, the strigoi are everything people fear of vampires with almost none of the traits that redeem them. Second only to mindflayers in terms of dangers, crossing one is known to lead to almost certain death. Unfortunately, joining or befriending one will often lead to death as well.

Physiology and Psychology
Strigoi are born in one of four ways, and each way is extremely rare, leaving these inhumans highly uncommon. These methods include: The low strigoi population is not just a result of general rarity, but also in the instinctual desire for strigoi who aren't mated to each other to fight to the death. Even a whiff of another can send them into a murderous frenzy that will only stop with the body of their rival. This, along with their intense emotions and poor impulse control, contributes to the fairly true conception that with the loss of their soul, strigoi also lose the logical side that allows vampires to pass for human. While inhuman is an already used term, strigoi become clearly unhuman, with minds and personalities that are wild and instinct-based in a way that can rarely be overcome by rationale or reasoning.
 * The complete deterioration of a vampire's soul due to evil acts (in the same way that deterioration of a human's soul makes a wight);
 * The theft of a vampire's soul by an undine or other soul-taking creature besides a demon;
 * Any being being turned by a strigoi (done exclusively to a strigoi's mate for reasons described below);
 * Random mutations during the process that turns a human into a vampire.

Despite this, strigoi retain the power of language, preexisting emotions and feelings towards others (and can form new ones, though it is not common for them to), a fairly human appearance, and even the ability to love. Strigoi mate for life and will never mate with another strigoi, although they seem to have no qualms about turning another being into one of them and many even prefer to. A strigoi in love is often dangerously obsessed with the object of their affection and will gladly use their dangerous abilities to "solve problems" for the one they love. As they are gifted at tracking prey and friends alike and especially tune in on those they love, escaping one ranges from extremely difficult to impossible.

The majority of strigoi are unsurprisingly evil, though due to their instinct taking over, there's movements to consider them as "unclassifiable" in terms of alignment. These movements have largely failed, mostly due to that while strigoi find it difficult and often not worth it to use logic, they technically still possess the ability to outthink their instincts and avoid murder and other illegal and evil acts.

Separation from Vampires
Often referred to as "super vampires," "mega vampires," or "twice vampires," strigoi nonetheless have major differences with the beings many of them used to be. Most notably is diet. Vampires greatly prefer human blood, and only human blood tastes right and provides the most sustenance. Inhuman and animal blood will keep them alive, but usually in poor health (pig's blood, however, is considered a passable substitute). Strigoi can and will drink any blood. In the event that a being has no blood, strigoi can drink the vitality and magic itself from any being, making them dangerous to all. In addition, strigoi feed more regularly, drinking blood once or twice a day rather than once every three to seven days.

Limits imposed on vampires also surpass strigoi easily. Vampires do not have base shapeshifting powers beyond shifting their fingernails into claws, nor base mind control abilities (though both skills can be learned and honed). These powers come naturally to strigoi, along with invisibility, shapeshifting into animals, and turning into smoke.

Society
As with vampires, strigoi will only willingly share territory with others of their kind if they are mated, though many keep a small group of other beings around them for protection, social interaction, and a food source. They are, incredibly, even more possessive of their people than vampires, and oftentimes will keep those they bring into their folds close at all times, even going so far as to kidnap and hide the people they consider "theirs," cutting all others in that person's life out. However, they are also known to kill these people without a second thought in the event of anger or hunger.