Concupiscence

Concupiscence, first called and often referred to as Freyja, or Lust, is one of the forgotten creatures that live in the forgotten world. She firstly was shown to represent Ziel's "lust", which is only displayed as love for her. However, it may be more bloodlust then anything else.

Personality
Freyja has two different personalities depending on who she is talking to; one when she's talking to Ziel, and another one when she's talking to everyone else.

When she's talking to anyone else besides Ziel, she displays distinct pleasure in torturing her opponents and making them suffer. However, Freyja did not display any personality traits based after her namesake. However, she did talk seductively to others and was well aware of her charm and used it to her advantage to set people against each other, trick them, or get information out of people. Her cardinal sin theme may have something more to do with her bloodlust in relishing those she considers beneath her to suffer.

She is arguably rather intelligent and patient, at least when it comes to Ziel. She tends to act calm and confident, but can become unhinged when pushed to a corner. She was loyal to Ziel, acted motherly towards Crying Child and seemed to have a good relationship with Fake Smile, but disliked Addiction.

Freyja also had a great disdain for humans, thinking them frail, predictable and generally foolish. Moreover, she would often comment on the ridiculousness of human nature. As such she felt no remorse over manipulating or killing.

However, while she exhibits this personality trait, Freyja has been shown to have a singular desire to become Human, which was revealed in the later half the series.

Magic and Abilities
Ultimate Spear: Freyja's unique ability was to extend her fingertips into long, flexible, thin claws sharp enough to cut through practically any substance with ease. The length of these blades is also undetermined and seemingly infinite in their range, leading to Freyja being able to kill her opponents at any distance with ease. Also adding to their lethality is the speed of which she can extend and retract them. However, they are not completely unstoppable.

Immortality: She does not age beyond her youthful prime.

Contaminant Immunity: She is immune to all poisons, toxins, venoms, viruses, bacteria, allergen, diseases, etc.

Enhanced Physiology: She possesses strength, speed, reflexes, stamina, durability, senses, agility, coordination, willpower, intelligence, and instincts superior to any human, chimera, or animal.

Enhanced Beauty:  She possesses a level of physical attractiveness, above that of most women. Using her enticing looks, Freyja plays the role of a manipulator within the ranks, moving covertly around the country to lure weak-willed people (usually vain people) into the clutches of their own lust, to be used and disposed of when no longer needed.

Trivia

 * Freyja's name is a reference to Freyja (translated as "lady"), the Norse goddess associated with war, death, love, sex, beauty, fertility, gold, and seiðr. She was also Queen of Fólkvangr, a place similar to Valhalla, where half of those who died in battle would go after death. Among other things, she’s credited with teaching witchcraft to humans, a practice seen as evil by the Norse. Her favored mode of transportation was a chariot pulled by cats.