The Lost

No one is quite sure why, but some adventurers just... disappear, while on their quest. Years later and thousands of miles away they may show up again, with no memory of why the other quest was abandoned, if they have any memory at all.

— Jasper Cameron, Leader of The Bronze Ravens

It has been known to happen, from time to time. A cruel trick of the gods some say. As the town is being attacked by raiders, or monsters from a nearby cave, or a princess has been captured, you all know the stories as well as I... anyway, along comes a party of adventurers, perhaps childhood friends, perhaps drawn to a tavern by some twist of fate. They assemble, grand speeches are made, chaos ensues, at least one building burns down. (For what sort of adventurer story would it be without a building burning down) Then the party of heros sets out and... nothing. The attacks continue, or the princess is forced to marry the usurper king. No bodies are ever found, nor do the raiders start using the much better gear that the adventurers had. No speeches about the fate of would-be rescuers.
Nothing.
These poor adventurers are The Lost, drifting aimlessly through the world. Whatever drove them to seek glory has fled and the fire that used to be present in their eyes is but the sputtering embers of a campfire abandoned to the rain. These poor souls are kept somewhat safe by their reflexes, fending off attacks and seeking out sustenance as a matter of habbit. Usually any communication with one of The Lost, if it can be called that, is in the form of vague gestures and grunts. Some villages have been lucky enough to "adopt" one that has wandered in, and are safer for it. Most, though, wander for years until some misfortune befalls them, their quest left unfinished.
Some of The Lost, it has been rumored, have regained that spark, many miles and moons from where it was lost. Perhaps another adventuring party finds them in a dungeon, and they go on to overthrow the tyrant and place the rightful king on the throne with a new group of heros. That is what I would like to think, anyway. It is a happier thought that them wandering endlessly, searching for nothing.