An Interesting Trend
I've noticed that in traditional fiction, especially fantasy, there's usually only ever one hero who stands out. It's Frodo who is the ring-bearer, Edward Elric who is the Fullmetal Alchemist, Luke Skywalker who is the destined savior of the Jedi, Buffy who is the Slayer, and that dual-wielding drow Drizzt who is the one and only exile of Menzobarranzen (and yes, I had to look that up...). This...well, it's not exactly how most RPG campaigns turn out.
In most RPG campaigns, everyone is special in some way or another. Everyone has a story to tell, and everyone has a role to play in the grand overarching story--but it's often an equal role, at least by default. Everyone wound up with that one destiny, or perhaps with separate destinies. Now, there's nothing wrong with that...
The Mark of Fate
...but what if there was a campaign where this wasn't the case? What if you ran a campaign where one character truly was the central character, where they had that special mark, or the destiny to rule the nation, or the hidden backstory with the Big Bad? What if you were in a campaign where most of the PCs were actually supporting characters? Well, that's a game that's rife with potential problems right at the start...
After all, what player would turn the spotlight 100% over to another player? It's not generally something that you want to do, right? After all, this is your character, and your character deserves plenty of chance to get a word in on how the story goes. Well...this is where the choice comes in.
You can choose for that not to be the case. What if, instead of approaching the game from the point of view of the character, you approached it from the point of view of the story? With this in mind, things evolve drastically. No longer are you scrambling to make your character in the image you desire. You're looking at the big picture, and how your character fits into it.
This requires a certain mindset and agreement from the players and the GM to work, though. You can't just out-and-out say "this is about the big picture, and not my character". You'll get trounced right out of the story by the other PCs. And that's not what you intended to happen. If everyone's on the same page, though, that lets plenty of things happen in the story. It can focus on one character, and also on the journey that has been given to that character. It becomes more cohesive. And in the end, you find something out...
You are not the star. The story is.
EDIT: An anonymous commenter had a very insightful bit to say on this topic. I'm putting it here for reference.
This shouldn't be a problem if you make certain your other PCs are like Wedge Antilles. Just because only one of the players will be running the character who will change history (or whatever) doesn't mean other characters are less important or capable. I'm reminded of the story of Cleitus the Black. Cleitus the Black saved the life of a man that would become one of the most famous men in history: Alexander the Great. Later he would fall under Alexander's spear. His fate was not to be a great leader of history, but does that mean Cleitus was historically unimportant?