After taking this to the plot bunny breeding pen I have made a few changes. PLEASE keep in mind none of this is written in stone. They are ideas for a plot. A story that should be a long term in depth rp that might take months to complete.
1. An immortal is someone like a Guardian of the world. I am thinking in broad
terms, like Highlander type. The only difference I am using is that this immortal can die, but the Spirit will reincarnate into another person. It does not mean it will be a female every time, but can be male. I have not worked out the details of it. I can also accept one body for this to play the entire rp.https://en.wikipedia.org/wiki/Highlander:_The_Series
2. Liattu Denariel is the name I chose for my character. She is an Immortal who has lost her power when the demon defeated her in battle. She is brave and independent, has the ability to fight and defeat lesser demons. She fights for the Good of the world, and destroys evil. Over the course of her many lives, she has become a little jaded. Allowing some blurring of the lines between what is good and what is evil. This is what opened her up to the influence of the Arch Demon, who seeks to destroy Good and sow Evil. She is not perfect, but the compassion, empathy and sympathy in her have lessened. Mostly she will see through false attempts to fool her.
3. When the Demon defeated her, he shattered her soul. Like a crystal it was divided into nine parts. Each part has become attached to a lesser demon. She must destroy the demons and restore the parts of her shattered soul. She lives on in the shell of her latest body by Will alone. Because she is weakened, she needs help in finding and destroying the demons. This is why I need a partner. To help her and sometimes Guide her.
4. Each piece of soul she recovers makes her stronger. But because of the demons, they will be tainted a little bit. So she will need to consecrate the pieces anew. She will need to make sacrifices and do quests along the way.
5. The Arch Demon of course will throw all kinds of obstacles in her way. He will require her to make painful choices, morally grey decisions which will make it hard for her to complete her mission.
(A partner can suggest quests and sacrifices for her to make, or even play the part of the demons she must defeat. Of course those will die as she recovers her soul.)
I want a writer who will not only challenge me to do my best, but who will enjoy setting quests and obstacles for MC. In effect, a DM who will make me work for each soul shard.
The smut can come so many ways, though I am not comfortable with NC or BDSM, it can be used here in moderation. MC can be seduced, or she can be encouraged to seduce YC. She can be forced into a situation where she has to comply, (Coercion) , or possibly bound and have to endure indignity or NC, but she will not enjoy it.
(Sorry I am not one who thinks a rape victim can turn around and love the rapist. It goes against everything I like about smut. If she has to endure this kind of behavior, she will get revenge on her attacker.)