Echoing: All You Need To Know

4, Princess Anastasia

"So long, miss you already."

Alliestar and Vallister, Vallister is Anastasia's sister, Valerie Star, which where the Brooklyn dead-flesh body name could've originated from.

but unlike her sister, Valerie was never in the spot light, always ignored and was always second best to her sister. So it could've been Valerie that made up the whole thing about Anastasia which led to her being killed, but later on people could've slowly found out that it was Anastasia's sister that caused all the drama which lead to her being executed as well.

So after life, since it reflected their past life, Vallister is just a inverted version of the original since what she did was terrible, (ps, Valerie became a demon because of the things she did in life, she was not created)
Anyways, skip forward.

Allie was born and Allie always stood out to some of the demons. . . .

Especially Vallister, fortunately for her Allie had a terrible life which led to part of her soul being trapped in the departed realm

Since Vallister was not created she sort of has access to that place, so she stole that part of Allie's soul (which was 6 at the time) and took her away, then created her own dead flesh body for her, created Ellie and putting her own soul + part of herself into it, so pretty much she was the original creator of dead-flesh bodies.

Alliestar did not know this which is why she was so confused on why Allie was getting weak so quickly, but eventually she would find out.

Somewhere along the line, she has to get rid of Ellie other wise Allie will fade away too quickly, so Alliestar goes on a hunt for Ellie.