Jada is Leeman’s half-sister and former princess of the famous (or infamous) Paradiso clan.
She was in charge of the clan’s presence in a particularly violent city, and Leeman was her confidante until he left the clan.
She continued to lead the organization until humans captured her and several other top officials shortly after Leeman left.
The humans forced them to succumb to servitude under the Compulsion Parasite, and so she was taken to a city far away on the other side of the desert to live out her life as a maid to a lecherous and greedy old man.
Adam and Leeman free her by murdering the guy, and she vows to free her other top officials and return the Paradiso clan to its former prestige.
She tries to get Leeman to join her, and even offers to help kill Adam, thinking that Leeman is under the influence of the Compulsion Parasite, but it is clear he is happy with his new life, so she leaves him to it.