A little context: Marie LaCroix is inspired by the real world religion of Voodoo, not the media depiction of practitioners of black magic. Her name comes from a mix of the real historical woman Marie Laveau "The Voodoo Queen of New Orleans" and one of the Voodoo Loa (Powerful Spirits) Baron LaCroix. Because in the Pokemon world Legendaries are treated as Gods I took some liberties with the depiction of Voodoo. Some but not all Loa were once living people of great influence like leaders of families, while others represent a fundamental force of nature like gods. Because that role is already filled by Legendaries, I am leaning more on Loa being powerful and influential deceased pokemon who take on an important role in the governance of the Spirit Realm and how the living and dead are able to interact between realms
I am not trying to culturally appropriate the beliefs of another culture, I have a genuine interest and appreciation for the Voodoo religion and want to depict it as accurately as possible.

Marie Lacroix was born as part of a long lineage of LaCroixs, part of the Gede family of Loa; Powerful spirits who represent the powers of Death and Fertility. of the Gede family are tasked with the noble duty of overseeing an aspect in the cycle of Life and Death. This can include (but is not limited to)

-Ancestor Worship/Allowing Channelers to Commune with the Dead
-Bringing spirits to the Living world for special festival days
-Maintaining and Guarding Cemeteries
-Guiding the dead to their place in the afterlife
-Sparing loved ones, especially children from dying
-Deciding when a person's time has come

and
-Meeting the spirits of the Dead on the other side and giving them peace that they have ed on.
This last one is the duty of the LaCroix family. The Samedi Family sends the dead to the afterlife and the Lacroix family meet them there on the other side to take care of the recently departed.

Marie LaCroix was meant to become the next head LaCroix Loa but she was a free spirit and forfeited the duty, because she did not like the idea of being forced to into a duty she did not want for her family just because it had always been that way, and would not force this duty on her own child. It's not as through somebody else couldn't take the role in her place so she wasn't leaving the dead unattended with her absence.

She moved to Treasure Town to distance herself from her family but remained a quiet voodoo practitioner, became a Baroness of Treasure Town and a very highly regarded socialite, but discovered she was infertile and could not have a child of her own...possibly simply medical or maybe a curse from family...she wouldn't know for sure but she suspected it was probably her family. Over the years she hired on many Salandits to work for her, and had many lovers including another Salazzle who lived close by but never married.

Then in her mid 70's she heard that a Salandit girl had been caught on the streets trying to pickpocket, and was now being held in an orphanage. She decided to go meet the little troublemaker a 7 year old Kaida who that day would become Kaida LaCroix. The two of them were exactly what the other had been looking for; Marie needed a daughter she could love and Kaida wanted a mother to be loved by. ittedly she spoiled Kaida more than a little bit but she always made it a point to be involved in Kaida's interests. Then when Kaida was 14 Marie got sick and ed away but her time being a mother was the happiest time of her life.