Into every character’s backstory, a few characters who aren’t the backstory’s central character must fall. They don’t live in a vacuum, after all. (And if they do, they’re probably pretty boring characters, and lack verisimilitude. Even hermits usually had someone who raised them.) That doesn’t mean they’re all created the same, though.
Overall, backstory characters are divided along two overall axes. (For ease of reference, I’m going to refer to the central character as whoever’s being backstoried, and the backstory character as any character who appears in that backstory.) One is the axis of detail—how well detailed out is the backstory character? In short, could someone pop onto the scene and be easily recognized as that character without actually providing an introduction? The other is the axis of proximity; how close (physically, socially, metaphysically) is the backstory character to the central character? In other words, is there any chance of the backstory character actually appearing outside the backstory? This creates four overall classes of backstory character.
First is the vague and distant backstory character. This character isn’t very well described, but that’s okay; you’re never going to meet him anyway. In many cases, the vague and distant character is dead, rather than being a hundred miles away—orphan heroes’ dead parents (or at least, the ones who don’t turn out to be alive through some metaphysical loophole) generally fall into this category, as do the various random townspeople from far away who had names but whom the character placed little importance on beyond sources of similes and who have no reason to show up.
Second is the detailed but distant backstory character. This character is pretty thoroughly spelled out—there has definitely been some effort, rather than a silhouette placed there because the character had to have had someone there—but not likely to appear as anything but part of a reminiscence of the past or a story of home. Some former mentors fall into this category, as do many lost love interests and the odd former companion who retired a long time ago or went to circumnavigate the world. Generally, they’re there to have had an impact on the character’s development but not to actively mess with the story.
Third is the vague but close backstory character—they’re definitely relevant, they’re likely to show up soon and Do Something, but there is next to no actual detail provided except that they exist. When used by a writer, they’re either not expected to do much important or meant to become Unexpectedly Important later; in RPGs, on the other hand, they’re very common, and used as an invitation to have the character used while trying not to scare the GM away from using them (or, in some cases, not setting the player up to be disappointed; more on this tomorrow).
Last is the detailed and close backstory character. This character is carefully detailed out, and very likely to be relevant—in a story, it is practically inevitable that she will appear, and in an RPG, it is extremely obvious that the character is meant to show up and be relevant.
For writers, knowing the categories means being able to balance between them; not all backstory characters need to be detailed and close, and having them all vague and distant makes the central character feel either unreal or like a bit of a sociopath, depending on the character. For tabletoppers, it’s even more important to understand, since what category a PC’s backstory falls in might be a hint to the GM to use them or to ignore them—or, conversely, knowing what a GM can work with can help decide what category to put a character in, as we will see tomorrow.