I go the opposite way. These are creatures of the afterlife. The afterlife of mortals, many of whom go on to become part of these creatures and/or develop into them. Sex in my opinion should be a part of their design.
From Pathfinder 1st edtion:
Petitioners are the souls of mortals brought to the Outer Planes after death in order to experience their ultimate punishment, reward, or fate. A petitioner retains fragments of its memories from life, and its appearance depends not only upon the shape it held in life but also upon the nature of the Outer Plane to which it has come.
Abaddon (Neutral Evil): The “hunted” have bodies that are identical to what they had in life—these petitioners are doomed to be stalked and eventually consumed by the daemons that lust for souls. A hunted that survives long enough eventually warps and twists into a daemon. The hunted gain DR 5/— and
fast healing 1 so that they provide a slightly more robust hunt for their daemonic predators.
Abyss (Chaotic Evil): “Larvae” are perhaps the most hideous of petitioners—they appear as pallid, maggot-like Creatures with heads similar to those they possessed in life. Larvae that feed long enough on Abyssal filth eventually transform into demons. They have cold, electricity, and
fire resistance 10, and instead of a slam attack gain a bite attack as appropriate for their size.
Elysium (Chaotic Good): The “chosen” have idealized versions of their mortal bodies. In time, after experiencing the pleasures Elysium has to offer, the chosen become azatas. The chosen gain resistance to cold and fire 10 and a +2 bonus to
Charisma.
Heaven (Lawful Good): The “elect” appear similar to their mortal forms, save that they possess a golden halo and feathered wings. After spending enough time aiding heavenly tasks, the elect become archons. They gain a fly speed equal to their base speed (average mobility).
Hell (Lawful Evil): The “damned” retain their mortal forms, but are heavily scarred by various tortures. Those who endure the torments of Hell long enough may eventually be approved for transformation into
devils. The damned gain
immunity to fire (but not
immunity to the pain caused by fire—whenever one of the damned takes fire damage, it must make a DC 15
Fortitude save to resist being
stunned by the pain for 1d4 rounds).
Limbo (Chaotic Neutral): The “shapeless“ retain their basic forms, but these forms constantly waver and shimmer, as if they were ghosts in peril of dissolving away. After wallowing in the chaos of Limbo for long enough, they can transform into proteans. The shapeless have the incorporeal subtype, an incorporeal touch attack, and all advantages granted by that defensive ability.
Nirvana (Neutral Good): The “cleansed” take on the forms of animals that closely approximate their personalities. Upon achieving true enlightenment, they transform into agathions. The cleansed gain cold and sonic resistance 10 and a +2 bonus to
Wisdom.
Purgatory (Neutral): The “
dead” appear as animated skeletons but are not
Undead—in time, they can earn the right to become aeons. They gain DR 10/bludgeoning and
immunity to cold.
Utopia (Lawful Neutral): The “remade” retain the same body shape but have milky white skin covered in dense black script, as if some strange scribe had used them for parchment. Upon deciphering the riddles posed by these complex lines of script, one of the remade can enter an axiomite forge to be transformed into an inevitable. The remade are immune to hostile
transmutation effects and gain a +2 bonus to
Intelligence.
So, once upon a time that Marilith use to be a mortal.
