The Jinni is a less complicated character than the Golem. We're not sure how he came into being, but we're sure how he comes to New York: He pops right out of an old flask, where he's been held prisoner by a wizard for a thousand years. He can touch fire, mold metal, and doesn't like water or the cold, and he's happy being alone, saying, "My kind can go years without seeing each other and think little of it" (14.167). To this end, he spends a lot of time being anti-social.
This whole anti-social bit isn't exactly acceptable in Little Syria, the neighborhood he finds himself in. In a neighborhood of immigrants, everyone treats everyone else as family, but the Jinni always remains an outsider. He's odd and quiet and keeps to himself a lot, preferring to prowl the rooftops and smoke cigarettes than sit at Maryam Faddoul's café and sip coffee.
All he really wants is to get the heck out of New York City. This makes him the opposite of all the immigrants there, who almost all ended up in New York by choice. They see the city as a path to freedom, but the Jinni sees it as a giant prison when compared to his desert back home.
The Jinni is good at a few things, like the craft of metalsmithing and the fine art of seduction. When he meets Sophia, a nice young lady in Central Park, he follows her back to her mansion, scales her balcony, and seduces her.
Then, well, the jerk doesn't call—he's just not that into her. He makes no effort to contact her, and as a result, he doesn't know that she gets pregnant and miscarries his baby. Oops. And because he has amnesia after popping out of the flask, he doesn't know that this is something he's done before. Classy pastime, Jinni.
In fact, the Jinni's philandering ways become a major plot point later in the book. He was careless with a Bedouin nomad named Fadwa back in the Syrian Desert. When he goes into her dreams and leaves her comatose, her dad goes to the evil Wahab ibn Malik, who turns out to be the wizard who imprisoned the Jinni.
Even though the Golem tells him, "Your life affects others, and you don't seem to realize it" (17.160), he only seems to change his ways when he realizes just how much his actions affect him. Because of this, if he had never been captured, we doubt he would have stopped being such a player with human women.
Unlike the Golem, who kind of wants a master, the Jinni wants to be free of his iron cuff, the wizard who trapped him, and New York City in general. The Jinni is used to being a shape-shifting spirit zipping around a vast desert, and New York City seems claustrophobic to him by comparison.
However, he's going to be in this human form forever since they end up trapping ibn Malik in the flask, because if they kill him, he'll just be reborn. The Jinni has to reevaluate his belief system, and redefine what it means for him to be free. Back in the day, Fadwa tries to convince him that there is joy to be found in human life, too, saying, "We can't all live in glass palaces" (18.245), but at that time, he's not mature enough to listen. Luckily, once he's stuck in human form, he has Golem to help him make some peace.
It's only when he meets the Golem that the Jinni starts to compromise his past life with his current one. The Golem ends up becoming his best friend—a source of true connection in a time and place he otherwise meets with resentment. She's a person who sees him for who he really is, both literally (a creature made of fire) and figuratively. She understands his conflicts and emotions because she, too, is just as much of an anomaly as he is.
The Jinni proves that he's willing to give human life a shot when he returns to New York at the very end. "I made a promise that I would return" (Epilogue.71), he says, and he does, even though he ends up traveling back to the desert that he calls his home. He realizes that he can't be around other jinnis, because they only remind him of the freedom he used to have. He can only be around humans (and his friend the Golem)… maybe because he feels superior to them. Okay, perhaps he still has some growing to do.