I don’t mind important secondary characters. Nor decoy protagonists who relinquish the mantle of main character to someone else later because to reveal the real protagonist early on would give the most important twists away. The characters I’m dealing with tonight aren’t those. Instead, they’re the ones who by all sources aren’t the main character(s), but whom the storyline itself treats as though they are; like a cuckoo in a different bird’s nest, they hatch early, shove the real main character(s) out of the way and demand as much of the spotlight as they can get. Because of this behavior, I’ll call them cuckoo protagonists.
Cuckoo protagonists seem to get the lion’s share, if not all, of the character development. Their needs, wants, joys and angsts—and particularly, their romantic plotlines—tend to shove their way into the spotlight and refuse to leave. Even their mistakes, as often as not, are for the greater good—and if they aren’t, then the character’s about to embark on a convoluted redemption plot to atone for whatever was permitted to go wrong. Another primary or secondary character might get a storyline or two, or share it equally with another character, but the cuckoo protagonist will have one To Himself, and it will get into everything.
Cuckoo protagonists tend to cause secondary and tertiary characters to orbit around them. If there’s a problem, they’re going to be involved in solving it. If there’s a potential problem, the other characters come to them, even if there’s someone more suited to solving it, even if the other character is characterized as being more close to someone else. Let me put it this way: if the character has a tighter relationship to a main character’s closest personal connection (particularly a personal connection that defines the main character) than that main character does, and it isn’t because the main character is a Lonely Lonely Loner Who Only Makes Vague Connections and this is a vital part of said main’s characterization, you’ve got a cuckoo on your hands.
Cuckoo protagonists may not necessarily be ridiculously competent—though a lot of them are, in order to justify what they do—but they tend to come across as either ridiculously competent or ludicrously fortunate. Either way, what makes this a cuckoo protagonist trait is the fact that they do it at the primary characters’ expense. In an RPG, they swoop in and drop massive hints—if they don’t solve the problem outright—before the group has had a chance to get it all together.
It’s not that cuckoo protagonists can’t always get away with it. If they really all are as cool as they’re trying to come across, and the audience isn’t invested in a given character as the main, it doesn’t come across near as much as usurping another character’s rightful place. The times you need to worry, though, are when someone might be invested. The more you-as-creator claim that one character is the main, the more the other character who seems to break in on her scenes (I am sadly accustomed to female leads acquiring male cuckoos; it’s a pet peeve) comes across as a cuckoo protagonist. Being a cuckoo protagonist is what separates the GMPC from the ubiquitous party satellite who just happens to be controlled by the GM, but a PC who doesn’t know when to give up the spotlight can also be a cuckoo.
Keep your eyes out for cuckoo protagonists in your own work; you never know when they’re going to sneak in.