Jinn was originally in service to the gods of Mulhorand, deities who have long since vanished from Toril. Several hundred years ago, he lived in the High Forest with his elven wife Quessahn Uthraebor but his peace was short lived as he was killed the following year.
In the years after the spellplague, he hunted down and killed members of the Vigilent Order, a sect of Asmodeus worshipers in Waterdeep. He had nearly eradicated the Order when he stumbled on a plot to finish the First Flensing, a ritual that would allow Asmodeus to enter Waterdeep.
Jinn agreed to help a Watch Captain friend solve a series of grusome murders in Sea Ward. While following leads, Jinn and his companions, the night hag Maranyuss and Quessahn, spent an evening at the Storm's Front Tavern. The dark angel Sathariel materialized on the second floor and started a fire which killed the Watch Captain and burned the tavern to the ground.
Jinn and Quessahn went to the Watch Captian's home and were magically sealed inside by the archmage Tallus who was working to complete the Flensing. Inside the house, they were attacked by Bodaks but Quessahn teleported them to safety in the sewers. While in the sewers, they consulted with an Avolakia named Briarbones who had tutored Quessahn in magic when she was younger.
Quessahn and Jinn later traveled to Tallus' tower looking for clues and were attacked by a guardian eidolon statue which they defeated. Later, Quessahn confronted and killed one of Sathariel's minions, Rilyanna Saerfynn at the House of Thorne where she was attempting to complete the ritual. Jinn battled Sathariel on the roof of the house and slew the dark angel by calling on the power of his enchanted sword. Using the power of the sword seems to have bound Jinn to some duty although it's unclear exactly what is required of him.
Jinn had a grudging alliance with an exiled night hag named Matanyuss. He was friends for years with Quessahn who was his wife in an earlier incarnation although he didn't initially remember the relationship from his earlier life.
Jinn wore leather armor and carries an enchanted sword which he stole from the Vigilent Order.
He had black hair, pale white skin with sigils covering his body and golden eyes.