So my two MC's are Super Villains in a comic book like world. He's like a demon (he used to be human it's a very long story) and she's like his servant and his biggest well she's like the Mercy to his Lex Luthor. The way they met was she was young and the victim a human trafficking and he started whispering in her ear. He basically built her up by talking to her telepathically telling her how to manipulate and kill her captors. He would often say "I can open up the door but you must choose walk through it." that's kind of how he helped her. She was abducted at age 13 and he started talking to her when she was 15 and basically she's been serving him for a while. She's very devoted to him and is a true believer in his vision and his vision is world under his rule. He desires to create a world free of "evil" and he's a total means justifies the ends type. She is an avid believer of the utopia he wants to create and she shares his vision because for her if he creates the world he wants to create what happened to her will never happen to anyone else. My problem is they aren't equals and neither has a problem with it. He sees her as a worthy servant and she well she's drinking his cool aid. The idea is that she sort of wakes up what little humanity is left in him. Now this is my problem I'm not sure if my Female MC will be as interesting because she's his groupie. This is there relationship she's willing to give up anything for him and he's willing to give up anything for her which surprisingly upsets her. She sees herself as disposable he doesn't see her as disposable at the same time he says things like "You belong to me no one else can touch you no one else can have." he says this to as strange as this may sound comfort her when she has a ptsd episode or nightmare about something that happened to her. Again though I'm not even sure how to develop their relationship because they are a pretty rock solid team.
Do you mean you want to develop a romantic relationship? That would creep me out because there's a strong power imbalance and he sounds scarily possessive and controlling, but there's definitely a market for that kind of abusive relationship (hi 50 Shades). I think you need to do what makes sense for these characters. To make the female MC interesting, for me you would need to give her some agency. She can't just do his bidding - she has to make decisions and act on her own steam. Those decisions can all be based around, "What's best for Male Character? How can I help him?" but she should be active, making things happen. A passive character is an uninteresting character. In a nutshell, your characters should make things happen, not have things happen to them.
Sounds more like a symbiotic relationship. As if she is possessed by the demon in some way? The demon gets what he wants from the MC and the MC gets what she wants/needs from the demon! But I'd agree with @Tenderiser the MC needs to make things happen otherwise you end up resenting the MC for being such a push over, rather than sympathise. Question: Is the demon malevolent or benevolent? If Malevolent, you could have it that there is an internal battle within herself, on one hand she recognises that what she is doing for the demon is wrong and her soul could be in jeopardy, on the other hand, the demon elicits the malevolent side of the MC to do his bidding, or the fact that the demon freed the MC she feels compelled to serve the demon.
I'm getting Death Note vibes here mixed with some Joker / Harlequinn. I agree with Tenderizer that the first thing you should do is give her Agency. I don't know enough about Harlequinn's character to speak on her agency, but Misa from Death Note had a ton of agency. Although she was deathly (heh get it) obsessed with Yagami Light, she was very competent in her own way and proved herself on many ocassions as more than just the "servant / obsessor". So basically the TL; DR version is to make your female lead more than just her obsession with your mob boss. (Side note: I am left wondering if this is a dead trope though, the main villain wanting to make a world without evil in their own vision who has a devout follower. I would be very careful to make this story unique and maybe look for more character driven focuses.)
It sounds more like he groomed/seduced her to his cause, but is it to her knowledge or by psychological manipulation? I don't get the Joker/Harlequinn vibe, since it does not sound like that type of abusive love/hate dynamic that works in favor of the Joker. I say this since your demon guy clearly seems to care about her, even though its through some pretty selfish reasons. So I don't get the notion that he would just ditch her if she gets stuck in a rough spot. Even if she were to insist that he not try and save her from it, for the good of the mission (so to speak). Though we don't really know their relationship dynamic on a romantic level, beyond his willingness to be over protective, and her blind devotion to follow. What I can gather is that they do have some type of mutual feelings, that are coming from two different places, but they do seem to be there. Or if even a romantic relationship exists. Even a one way one. I think I would have to agree with the others that she does need some agency and individuality to have a more robust dynamic about her, and be seen as more than just a groupie to him. Also how do you want her to come off as to the reader? Sympathetic, or more of a fun twisted type, that only serves the purpose of her enforced type devotion and furthering his agenda. Even if it is misguided.
Where you go with this will depend entirely on what themes you want to get across in the story. Twilight is in no way a good book, but some of the decisions that Stephanie Meyers make, make sense when you take the stories themes into consideration: which is the fantasy of forbidden romance in a nice PG Mormon sort of way... A story where you're trying to say that compassion can be developed as we think of others as our equals as opposed to those we can dominate, will read a lot different then a story with the same premise, but it's theme is that no controlling relationship is good, even if you gain something from it. So figure your theme first, then figure how the relationship will go, focusing on that theme.
He's not malevolent but he's not benevolent either. He kind of falls in between he's more about punishing what he deems evil. For him though evil is a very broad category. His idea of a utopia is a world where there's no free will, no crime, no freedom speech and of course a world he rules. I want her to come off as sympathetic but at the same time she's very twisted. She's a sexual sadist and enjoys control and takes it to extremes like I don't know if PTSD is the right word for her but her mind will take her back to something that happened to her and she'll just really lay into whoever she's torturing. Inflicting pain is how she releases her own emotional pain. Now the people she tortures can vary but usually they are her master's enemies. A way I was planning on building on her was to have her and him get separated at some point. A key thing about her is that she misses her family but doesn't want to see them because she's become someone they wouldn't recognize.
You may want to look into Stockholm Syndrome, if you want to make the female protagonist a bit more sympathetic. Basically, she would not follow this guy under normal circumstances, but he saved her from a horrific situation and has taken care of her in such a way that she has become his. She is his prized possession. He will fight for her because she belongs to him and she is the perfect tool for the job. This is my takeaway from your question.
Separating her from the MC would be a good opportunity to develop agency in her and also expand on the how the MC feels about her, I don't know where you want to go with these characters but because you want her to come off as sympathetic I think they could arouse the good in each other. It could develop a scene where their developing relationship could change both of their outlooks when they have a reunion. With her feelings for her family serving as another development in this direction. There are a few paths to take and depending on how you want it to resolve the rest is up to you, so I hope I was useful.
I would write her as a severely dysfunctional Enneagram Type 2. This is... she is worshipping him, loving him, doing his bidding etc BECAUSE she know this actually gives her power over him on some level. She doesn't feel safe to face the world alone, he is a strong 'go get it done' type of person (Enneagram Type 8), so she goes to him for protection against the big bad world. But she sees his hurt and dissastisfaction that has led him to want to wipe out the evil in the world (what happened to him that was so traumatic, there needs to be something). So instead of seeing him as the destructive maniac he has become, she sees him as the hurt little boy he once was, and she gives him all the nourishing and ego boosting she thinks he would need. She makes extreme allowances for his behaviour because 'he is hurt in a broken world and doing his best to keep us safe'. Because she is so good and soft to him and soothes his ego all the time, she actually makes him WORSE. She enables his destructive behaviour. So she goes between seeing him as 'hurt little boy' and 'hero of the universe' and thus she gives him constant ego boosts and allowances for any and all type of behaviour. She also adores him because she has so much pent up rage and he gives her 'permission' to be sadistic, while still being his 'little'. This gives her a feeling of safety and security even in her most wild moments where she could scare herself if he wasn't there. There should be times when he deliberately hurts her and then SHE is the one to fix it. She basically allows him to take NO responsibility for his actions whatsoever. She won't take ownership of her dark side - it is all projected onto him. They are actually equals underneath - he is very dependent on her ego-boosting to give him energy and confidence to fulfil his mission. She is very dependent on him for protection and for her to live her darkness through vicariously. They are feeding off each other.
For the above to be realistic, he'd have had to go through a significant parental loss such as sudden parental death at a young age, for example. She'd have had to have emotionally unavailable caregivers whom she was always trying to win affection from, or abuser parents who she was always trying to appease.
With her saying she's disposable... She says this because she wants to glorify him, i.e. 'you're the glory of all this, not me' but secretly she knows this is not the case. She is saying it to be 'good', to be 'perfect', to be a martyr, a perfect worshipper. But underneath he is massively dependent on her and SHE KNOWS IT.
