The majority of bodies on the planes are petitioners, which are departed spirits of primes and planars whose bodies reformed on fhe plane that matches their previous alignment or devotion. A petitioner retains the mannerisms, speech, even general interests of his or her former self, but all memories of the past are wiped completely away. At best, a petitioner has a shadowy recollection of a previous life, but little or nothing useful can be learned from these fleeting images.
Petitioners mostly desire to attain some ultimate union with the powers of their plane. This can be accomplished in a number of ways: good works, serene contemplation, steadfast faith, or vile notoriety, depending upon the petitioner’s alignment.
Petitioners hate leaving their home plane, as "death" outside that place results in oblivion. Fact is, they can’t be resurrected if slain at home, either; once dead, the petitioners’ essences are merged with the plane, but they figure that’s better than nonexistence. Still, a power's got to raise an army now and then, and it may be petitioners that fill out the ranks, but that’s the only way they'll ever leave their home turf - on the boss's orders.
Petitioners tend to view all things as a test of character. They ain't eager to die, but they’ll take that risk in order to further their own goals. For example, a petitioner warrior on Ysgard will fearlessly rush into battle, since combat is the glorious and right thing for him to do.
Note: Petitioners originally appeared in this form in the Planescape AD&D campaign setting from TSR. Their use here is for the purposes of providing context for the campaign only.