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.

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. If a petitioner did not have a specific patron deity in life (most mortals were polytheistic), they were taken in by the deity who was most closely aligned with their moral and ethical outlook. Those who never paid homage to any deity, or betrayed their god, were deemed Faithless or False.

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
A normal petitioner served its deity and interacted with their realm in varying capacities, based on the nature of the deity they served. Petitioners didn't usually remember their previous life, though there was some evidence to suggest that they retained strong emotions connected with those they knew in life, such as past lovers or family members. If their loved ones followed the same deity, or pantheon, they could be reunited.

Some petitioners were remodeled upon entering the realm of their deity. For example, followers of an elven deity took on the form of elves with exaggerated features, even if they weren't elves in life. A similar thing occurs with petitioners of the dwarven deities. Barring resurrection, a petitioner could not leave the realm of their deity, though allied deities allowed their petitioners to mingle with loved ones who served another deity. While most resurrected petitioners didn't usually retain their memories of their time being dead, Fflar Starbrow Melruth retained vague memories.

Normal Petitioners' Duties
As mentioned above, a petitioner served their deity in varying capacities, based on the nature of the deity. Some had a more relaxed afterlife while others were called upon to defend the realm. Petitioner pursuits could be similar to those it had in life. For example, petitioners of Oghma will pursue knowledge in the vast libraries of the Hall of Knowledge, while petitioners of Tempus will engage in battle.

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 (though this is rare, as the deities are very active forces on Toril), 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.

Demons were also tolerated by Kelemvor to attack and take some Faithless from the Wall of the Faithless and subsequently raid the City of Judgement to kidnap some False with them. Kelemvor, as mentioned before, tolerated this but moved against the demons when collateral damage became too high for him to endure. 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. They not only retained their skills from life but could also leave Vhaeraun's, realm Ellaniath.

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