The Vault Dweller was special because of his/her determination. The Vault Dweller kept going forward to save his/her people, spitting in the face of common sense, well-meaning advice, and life-threatening injuries. That, and it was kinda "fail, and everything you've ever known and cared about will be taken from you!". Even though that happened upon victory as well.

Having not finished FO2 or Tactics yet, I will not comment on The Chosen One or The Warrior. Except to say that I can't seem to get Tactics. FO1 & FO2 are both freaking easy in comparison.

The Lone Wanderer was special because he/she existed in a region inhabited solely by morons, Super Mutants, & the Designated Villains(maybe the radiation had something to do with that). That said, credit must be given to the LW where due. The LW was surprisingly resistant to all kinds of damage, which has something to due with his/her success.

The Courier....was special because he/she was able to track a man across the breadth of the Mojave for mere vengeance! The Courier got up from a double headshot, found his/her way to Vegas, and at that point, the major factions, with their intel databases, began to see The Courier as special.

In short, The Courier was tough and lucky, the LW was the only non-stupid non-Enclave human, & The Vault Dweller's heart wouldn't let him/her stop.

-Nukeknockout

He waa drawed by his shortest straw.

This is why Fallout Online would be interesting, and not a bad thing.