From Fan History Wiki
At the time the series is set (1998-2000), Dan is 28-29 years old, a few years younger than his co-anchor. He comes from Connecticut and attended Dartmouth College, but considers himself a native New Yorker. He is Jewish, left-handed, and has a passionate dislike of soccer. He is, however, a serious sailor, and is the show's acknowledged expert on water-orientated sporting activities.
Dan's life is overshadowed by the tragic death of his brother, Sam, two years his junior, in a car crash on the same day that Dan left for college. Because Sam had been drinking and smoking marijuana at the time of the crash and Dan had, in his own words, 'smoked a lot of pot' as a teen, Dan blames himself for the tragedy. Perhaps as a result of this he has a difficult relationship with his father, Jay. In the episode The Apology, a magazine interview gives the CSC network executives the impression that Dan is advocating drug use and forces him to make an on-air apology, in which he blurts out Sam's story to the world.
During the course of the show's first season, Dan falls in love with a CSC market analyst, Rebecca. A few weeks into the relationship she admits that she is not, as she had claimed, divorced from her husband, but only separated. She later leaves Dan to go back and try to repair her marriage.
Dan is very close to Sports Night's managing editor Isaac Jaffee, and is devastated when Isaac suffers a stroke (Eli's Coming).
In the second season of the show, Dan suffers a nervous breakdown and begins to see a psychiatrist, Abby Jacobs, whose treatment only appears to exacerbate the problem. It comes to a head in the two-part episode Draft Day, where Dan has a meltdown on air and alienates Casey and his other co-workers. Reconciliation is achieved in the following episode, April is the Cruellest Month, against the background of a Passover Seder.
In the final few episodes, Rebecca returns, and the show's future is threatened, leading Dan to contemplate taking a job in LA. He tries to persuade Casey to come too, but Casey refuses to leave his ex-wife and son, telling Dan "You can make it without me." "This is it?" Dan replies, devastated.
Dan's primary character trait is his kindness: in the course of the series, he offers support and comfort to almost every other character when they need it, including Casey, Natalie, Jeremy, Rebecca, Casey's son Charlie, Dana, Sam Donovan (the ratings expert brought in in season two), and even Sally, a generally unsympathetic character.
Fan fiction tends to slash Dan with Casey, sometimes with Jeremy, and quite frequently with original male characters. There is also a sizeable body of het fiction that partners him with Natalie.