Very little is really known about the woman that calls herself Mistress Libra. She likes to say she is either the wife, daughter, and/or lover to the cosmic force known as Libra, but in truth she is a pretender. She is known to have lied about almost everything concerning her life, including her powers.
Libra has said in the past that he is aware of the young woman's actions and that he tolerates such games for the time being as he somehow gains recognition and respect from them. She was even allowed to be a member of the group he sponsors, The Libra Order; but according to Tainted Eve that was only done so they can better keep an eye on her.
She is clearly not to be trusted.
Time and Changes
At the conclusion of the "Time and Changes" storyline of the Guardians of the Dawn Spotlight series, Mistress Libra was seen talking with the alien collector known as Bartiok and suggesting he look into a "rarity" known as "The Guardian Exiles".
In "The Libra Order: Debts Of Honor", we learn from Libra that the Mistress holds an almost equal position in the order to that of Tainted Eve. Libra describes her as being an "Agent of Chaos" to counter Eve's status as an "Agent of Order". We also learn that she goes by the name Lilith.
Powers and Abilities
Mistress Libra's primary ability is Demon Summoning. She can use magic to summon demonic minions to do her bidding.
Her secondary ability is Pain Domination. She is able to inflict pain to either help herself or to harm others... preferably both.
In addition to her mystical powers, she also possesses a whip which she can use to inflict pain or to empower her minions.
The best description of Mistress Libra's personality is that of a sociopath. She is completely amoral, willing to do anything she can to get what she wants. She is masterful at manipulation, being able to twist the sensibilities and emptions of others to her benefit.
Her outfit is deliberately provocative, designed to catch others off-guard and make them feel uncomfortable around her.
Question of Sexuality
In "Debts of Honor", there is a scene where Mistress Libra tries to seduce Tainted Eve in the Libra Order's pool area. While Eve rejects her offer, "Lilith" comments that she's seduced more than one angel in the past, not mentioning if these were male or female angels.
According to creator David 2, Mistress Libra is using seduction as a diversion, which, as a sociopath, is separate from sexual preference. The seduction is merely a means to an end for her.
Although not seen, she is referenced in Issue #17 of the Guardians of the Dawn Spotlight series. Her first physical appearance was in Issue #22. She was later seen organizing villains to attack Galatea Powers in "The Guardian Powers" while keeping herself out of any danger. All of it supposedly at the behest of Libra.
It is not known if "Lilith" is really her name or if it is yet another way to provoke Tainted Eve. In Jewish mythology, "Lilith" was the name of the actual first woman created after Adam. This contradicts the Christian Biblical accounts of Eve being created as the "first woman", which explains why all references to Lilith were removed from the Old Testament. Since Tainted Eve was the "model" for the Biblical Eve, the use of the name "Lilith" could be seen as an insult to the fallen angel, placing her "before" Eve in the eyes of Libra.