The big comic publishers have a long history of whipping up gimmicky storylines in bids for attention, news coverage, and a corresponding boost in sales ("Superman, is he really dead?"). Marrying a popular couple is a good one; see 1987's marriage between Peter Parker (better known as Spider-Man) and Mary Jane. Over on the DC side nearly a decade later, there was Superman (alive and well!) and Lois Lane dropping the enduring-yet-bizarre love triangle with alter ego Clark Kent and finally tying the knot. These things are never destined to last, of course—witness the somewhat desperate backtracking on Marvel's part to erase Spider-Man's marriage.
Looking to stir up some of that juicy publicity again in 1992, Marvel skipped the marriage route, let the tired, massive character crossover events take a break for once, and instead decided to out one of its characters as gay. The spotlight fell on mutant hero Northstar, a member of Canadian team Alpha Flight, and an on-and-off-again X-Men teammate. This wasn't exactly a shock to anyone who followed the character—there had been sly nudges and winks aplenty for a while (including a strangely aborted AIDS storyline), but a comic book hero holding a press conference (the action takes place in Alpha Flight #106) to announce his sexuality generated plenty of real world press, as, one imagines, Marvel would have hoped.
This storyline appeared a year before Don't Ask, Don't Tell—the United States policy on gay men and women serving in the military—a particularly relevant piece of real world legislation when it comes to talking about someone who isn't straight putting their life on the line to save people, be they fictional or otherwise. At this time there was no Will & Grace putting gay characters into the mainstream and Ellen DeGeneres hadn't made television history by coming out (in character) in an airport. Comics like Frank Miller's Batman: Year One or Neil Gaiman's The Sandman were slowly breaking down the popular perception of comic books as purely a children's medium, but the notion of a gay hero was still one that generated plenty of ink and controversy. (That's right, ink—this was 1992.)