I talked yesterday about mutually dependent characterization, ending my riff with the idea that there are, in fact, risks as well as advantages to it. But what are they?
The first is utterly inseparable characterization. This most often happens when characters are designed as a set, rather than growing together naturally—they become so much of a pair that they become almost incapable of doing anything as, or even treating themselves as, separate entities. They’d defined by each other, will answer a question about how one is doing with how both are doing, and in general come off as a single character who happens to inhabit two bodies. (Blogger’s note: if what you intended was a single character inhabiting two bodies, make sure there are indicators that it was intentional—and please, tell me how it went.) This sort of characterization is a particular problem for twins, background couples, and just about any character pair initially designed as a set.
The second issue is one-sided dependent characterization, where half the pair is showing definite signs of mutually dependent characterization traits, but half seems exactly the same as they would be without the other half of the pair. I’m not going to say this is all bad—hero worship and unrequited love from afar happen, after all, and if you’ve got distance and no reason for the characters to have met more than once or twice (if at all), it makes perfect sense. On the other hand, if you’ve got a protagonist who leaves a train of dependently characterized characters in her wake, none or very few of them having much if any effect on her characterization at all, you might be veering into Author’s Darling territory.
Then there’s the issue of mutually dependent characterization at the game table, particularly where PCs are involved. Most of the players who are in it for the characterization would find acquiring a character or two with dependent characterization traits pretty flattering: it shows they’re having an effect on the world. But that does mean that, like other resources distributed to PCs, you’ll want to keep an eye on the balance: if one person’s getting nemeses and recruits to the cause by the barrelful, you should try to dangle potentials in front of the other characters and give them a chance to bite. This goes double if you’ve got a party NPC making lots of mutually dependent characterization sorts of connections, particularly if those connections are with NPCs the players rather like. Give someone else a turn!
So keep it natural, try to keep it mutual, keep it well-distributed if you can, and you’ll have room for plenty of fun with mutually dependent characterization.