Obsidian is a dark hero that was seen with the JSA, and the JLA. Oddly, sometimes they were fighting, and other times they were allies. The general populace may not know exactly where Obsidian's loyalties lie, and with as creepy and scary as he is, maybe some aren't really eager to find out...
Alan Scott and Alyx Florin (a.k.a. Rose Canton, the reformed Flash villain Thorn) are married. But Rose's "Thorn" personality resurfaces and she allows Alan to believe she died when their honeymoon cottage burned. She later discovers she is pregnant with twins, a boy and a girl. After giving birth in Milwauke, gives the twins up to different orphanages.
The boy is adopted by Shirley and James Rice, who had been unsuccessful in having children, and named Todd. Not long after adopting him, the Rices produce a child of their own, who they name Jeremy. James is not prepared for the hardships of raising TWO children, and begins to drink.
Shirley makes plans to divorce James. Todd tries to dissuade her, for Jeremy's sake, which Shirley interprets as "taking James's side". So when she leaves James, she takes Jeremy with her, leaving Todd. James is an abusive, drunken father; while James sleeps off his drunken benders, Todd discovers his powers and begins to practice them.
In his late teens he and Jade discover each other again; they have suspicions that the Golden Age Green Lantern may be their father, but neither have concrete proof.
As "Jade" and "Obsidian", the two apply for membership in the JSA. They are initially refused, and after the JSA dissolves, the two form the group Infinity Inc, composed of the legacy members of the JSA. After many adventures, Infinity Inc. was also disbanded, and Todd went into retirement.
Todd's connection with the Shadowlands, and that he can only see the darkness in people's hearts gradually causes him to lose his grip on sanity, and he plots revenge against both his adoptive and biological father. Ian Karkull used this to turn Obsidian evil, and Obsidian subsequently begins to try to bring darkness to every corner of the Earth. A sacrifice by James Rice and a long battle with Alan Scott that ended in Obsidian's defeat stops him. Obsidian retreats to the Shadowlands.
Obsidian joins Mordru and Eclipso to get revenge against the Green Lantern and the remaining JSA. He is defeated again, and his sanity is re-established.
Todd retires from heroing, to turn his attention to his personal life. At a charity auction, he meets Damon Matthews, assistant district attourney and co-counsel to Kate Spencer (Manhunter), when Damon inadvertently spills his drink on Todd. Later Todd is forced to come to terms with his sexual orientation, due to his attraction to Damon.
Todd and Damon begin dating. Damon is initially unaware of Todd's double life as Obsidian, until he sees a holographic image of the Golden Age Green Lantern in Todd's house, which Todd refers to as "Dad". Todd comes out of retirement as Obsidian.
The two are still dating; Damon acts as the grounded one. Damon is supportive and optimistic about Todd's career as Obsidian, and Todd is learning how to be "happy".
Troubled: Let it be said first that, despite all his problems, Todd IS a good person. He cares enough about his fellow man that he would want to use his powers for the betterment of all. He's just quiet and doesn't seem to really know how to socialize all that well, and that could lead people to believe he doesn't care. He isn't anti-social, he just doesn't "people" super well.
Schizophrenia: Todd has, unfortunately, inherited some of his mother's mental problems -- her schizophrenia, not her multiple personalities (thankfully). At times he may suffer from any of the following: he may have trouble expressing his emotions, he generally speaks little, doesn't usually feel any pressing need to make new friends or keep current friends around him, and sometimes has trouble getting the motivation to do things.
Temper: He also has a temper, and is also prone to violent outbursts when that temper flares. While his temper may be something he just has to deal with, the violent outbursts may be learned behavior, and as such could be a habit that can be broken. There is, however, a tremendous amount of rage inside him, and it boils close to the surface at all times.
Kindness: It would be incorrect to say that his childhood taught him nothing but bad habits. While he may have learned that dealing with anger always involves violence, he also knows what it feels like to be on the receiving end of that violence. So he's going to make certain not to put anyone on the other end of his violence that he doesn't feel deserves it. Criminals, people who would prey on the innocent -- he'll be aiming his rage at those kinds of people.
Impulsive: He likely turned to heroing partly to help other people and partly because his rage needs a victim. Beating up people that are already reprehensible seems like a good way to get the aggression out. Mind you, he hasn't (and probably won't) consider the consequences of this sort of behavior, whether it's illegal, etc. And he's not likely to let himself think about the fact that those people have families, or that he's so much stronger than they are, particularly in his shadow form. This is a really bad combination.
Reckless: Add to this that Todd's quite reckless and tends to not think about the consequences of ANY action. He really IS a good guy, and he tries hard to do the right thing, but he is impulsive by nature and tends to just "go with it" if a decision seems like a good idea at the time. Without guidance, Todd's recklessness and penchant for leaping into action first and asking questions later is going to get him in serious trouble, even if he's trying to help.