Tell me how this sounds...

My main character is part of this family, but she looks nothing like her siblings or her mom. The drawings and pictures of her dad don't really reveal anything similar either. Her mom says they have the same eyes, but there are only so many colors one's iris can be. Truth is, she was found on the road and the couple took her in.

Quick background: there's a sacrifice every year, she is the one for this year. The reason for the sacrifice is to thank the gods whom the survivors created after all the old gods were killed in the demon invasion. The gods don't actually kill the sacrifices but let them live in their utopia.

The girl is actually a demon that was planted in the human world so that her real family, her people, could see everything that she saw (though she doesn't know). The demons decide that the society and gods are still weak enough, while their ranks have regrown, so that they can now finish what they started. It helps that they know the secrets of the utopia.

But in the end, our main girl will have to choose to either side with her heritage (demons) or with her home (humans). She has to choose which side she will fight for.

i mean, i like it. i do. it just sounds kinda… mary sue-ish. you should fix your wording, instead of using demons (because yes, "demon" is not the correct term. you cannot be a demon and look like a human, that is a shapeshifter.) you should probably use "demoness" or maybe even "succubi," if that's the type of demon you're using.

also, you should adjust the third paragraph, where it says, "the girl is actually a demon ("demoness") that was planted in the human world so that her real family, her real people, could see everything that she saw (though she doesn't know)." tell me, WHAT does this imply? were the girl's real family searching new information on earth, on humans? WHY did they choose that girl, and why doesn't she know her original heritage?

and you should also look over the part where it says, "the couple found her on the road and took her in." if you saw a baby in the middle of the street, would you pick it up and raise it as you own? i don't think so. not even in the ancient times did they do that. so maybe, if you're aiming a setting a little more modern, make something that you would do. would you question why a baby was there and maybe leave it? then write that, and make the couple's reactions a little more "natural" to what is known today.

also, WHAT is she fighting for? i understand that this could just be a saying, but you can simply choose to be with both species at the same time. i recommend that you also fix the backstory, and the beginning part. i hope you take some advice from this critisism, and i hope you improve!

this is just like a general idea…lol
thanks for the insight, but none of what I wrote will actually be in the story, this is an idea for the story.
But thank you, when I do turn it into what I need it to be, I will keep all of this in mind :)

Interesting concept, it feels very fairy-tale-ish (the demons thing especially, lots of Western fairy tales liked "Christian" elements in their stories). Except why do they have to be "demons" specifically? Can they not just be a different race or creature from a different realm? Maybe just evil spirits or evil gods? So does she "die" and go to the Utopia?

Well it's sin in material(ish) form, something that can fight. I don't know exactly how or what I'm gonna make it