Petitioner

Petitioner was the term applied to a dead person's soul that made it in some way or another into another plane of existence than the Material Plane.

Becoming a petitioner
Upon dying, a mortal's soul was transported to the Fugue Plane. Once there, these souls counted as petitioners but didn't have the attributes of one yet. They became full petitioners after entering the plane of their respective deities. A soul was taken in by the deity it served in life, or, barring having a patron god, the deity who best fit its ideology and moral and ethical outlook

Other petitioners received judgement from Kelemvor. The standards according to which judgement was handed were whether, which,and how honestly someone followed a certain deity during its lifetime.

Normal Petitioner
Normally, a soul of a dead mortal went to the Fugue Plane. Once there, it waited until the deity it followed during lifetime or an agent of the same came and took it to its final destination, that is, the realm of its deity. In the deity's realm, the petitioner became a full petitioner with all the attributes of one.

Normal Petitioners' Attributes
Petitioners don't often remember their former life, though they sometimes retain memories of past relationships with others, particularly if that person is of the same faith.

Upon resurrection, most petitioners do not remember their time in the afterlife, though there have been instances of resurrected souls retaining vague memories, such as Fflar Starbrow having vague memories of his time in Arvandor.

Normal Petitioners' Duties
The duties of the petitioner will vary based on the deity they serve, and can range anywhere from simply enjoying their time in the realm, to carrying out specific orders from their deity.

Different Types
Different types of petitioners existed.

Faithless
A Faithless was the soul of someone who'd never believed in a deity, for example by not knowing that they existed during their lifetime, or only paying lip service to one. They were sent to form the Wall of the Faithless as its bricks for punishment for their lack of faith by Kelemvor. They were eventually dissolved by the wall but could, at least in theory, leave the Fugue Plane.

False
A False was the soul of someone who intentionally turned from their faith in life. These were judged and punished according to their deeds in life. The punishment was enacted by Kelemvor and Jergal but the content was determined by the deity the petitioner swayed from. It always included an assignment as the eternal labor force in the City of Judgement. The punishment ranged from something light, such as to work as an escort, to the sort of torture that demons were incapable of coming up with.

Kelemvor allowed a number of devils to randomly torture citizens of the City of Judgement. The only one who could stop it was Kelemvor but he was known for never doing this.

A False couldn't be resurrected without the consent of the deity from whom the soul swayed from in life and only after that deity negotiated with Kelemvor.

Like the Faithless, the False were also capable of leaving the Fugue Plane, all at least in theory.

Others
Devils were allowed by Kelemvor to negotiate with souls while they were on the Fugue Plane. These souls could bargain for a position in the Nine Hells, starting at the bottom as a lemure or somewhere higher depending on the power of the soul and outcome of its bargain.

Petitioners who were brought into the Abyss became manes and, unlike other petitioners, were capable of leaving their plane, that is, the Abyss.

A vhaerath was a special type of petitioner who followed Vhaeraun, could leave Vhaeraun's realm, Ellaniath.

Some worshipers of the gods Tyr, Torm, and Ilmater became lantern archons when they died.