Ruelia is the overseer of the Underworld and a collector of souls. Her duty is to turn the souls of the dead back into energy that is meant to be returned to the world, however, she also collects souls to fuel her own energy. She does this by forming pacts with the living and grants them wishes in exchange for their soul to be consumed by her. Ruelia does not have any empathy for the mortals of the world and is only interested in performing her duty and gathering souls for herself.
Ruelia takes a form similar to a drow elf. She has pale-blue skin with silver hair and light blue eyes and she wears a tunic because it's comfortable.
Ruelia originally only created stealthy Diamalis that lurked in the shadows with the purpose of teaching vulnerable mortals the ritual to form a pact with her. Later, Ruelia had begun to create more vicious and powerful Diamalis that temporarily served those who wanted to summon powerful creatures to do their bidding.
The ritual used for mortals to communicate with her are fairly simple. A knife, a living offering and a cup of wine is all that's needed. The knife is used to cut the caster so they can use their blood to draw Ruelia's sigil. The wine is then placed in the sigil. Next, the offering must be killed within the sigil while saying "For Mother Ruelia." Finally, the caster must drink the wine and sleep to talk to Ruelia in their dreams.
This allows the caster's soul to travel with the soul of the offered creature to the Underworld. The sigil and words allow Ruelia to separate and pull the caster's soul to her chambers. If the ritual is done incorrectly the caster's soul may never return. The wine helps return the caster in case anything goes wrong.