Movie script: Absolute power

Sometimes I imagine if I could be a movie director and make some film. The first problem is the script. What kind of story should the film be about?

I had thought of a story of 3 sisters, with super-powers, able to fly and immortal. Ok, I confess, I spent my childhood reading too much comic books.
And my story seems to come right out of a comic book.
What if you were immortal and had super-powers, what would you do?

Sister number 1 decides to save humanity and bring peace to the world.
Sister number 2 decides to become human, to get married, have kids and lead a normal life.
Sister number 3 decides to solve the mystery of their origin, and sets out on a jorney to search their parents and the story about their birth.

Hundreds of years later, sister 1 becomes Empress of the world, the most cruel and ruthless tyrant the world has ever seen, willing to slaughter any opposition without hesitation.

Sister 2 utterly forgets she is immortal and after the death of her husband and family she lives alone in a decrepit house in the middle of the forest, wasting the days remembering the happy days when her husband and kids were alive, waiting for the time she dies and is finally able to rejoin her family, waiting for a death that never comes.

Sister 3, after hundreds of years travelling all over the world looking for any clues about her origin, finally returns to rejoin her siblings. She has made one startling discovery, that they are not actually immortal, that there is only one way for them to die:  by killing one another.
However she lost her sanity completely and returns determined to destroy her sisters.

There is no need actually to be 3 women, it could have been 3 guys, but I like female characters, and in my movie I'd like to have  all the lead characters as female.

Why the power to fly? Because I like films like Superman? Again because of the visuals, visually it would be very exciting to have 3 beautiful actresses with the ability to fly. We don't have many films like this... Superman is a guy, Matrix is also a guy. In X-Men Storm can fly but her flying sequences are very poor. There are very few films with leading female characters with super-powers.

Why immortality? It has to do with the plot, and the end of the film, where it is revealed sister 3 is not crazy, she actually knows the secret to their existence, and it has to do with the fear of death, and the ultimate challenge in life, to overcome the fear of death.

Scene 1 begins with a shot of the 3 sister as teenagers flying all over the world and having fun. It is a idyllic time. They are immortal, they can't die, they can't get hurt or harmed in any way. They can stand the heat of the deserts, the cold of the poles, they don't starve, don't need to eat nor drink. They don't get sick, don't get hurt, they can just throw their own bodies into objects and destroy the objects instead of their bodies. Their bodies are indestructible. They don't drown, they can stay as long as they want under water without breathing. They are happy and they laugh all the time.

Scene 2 is about their talk about life and future. What should they do with their lives? That is when they decide their destinies, and each chooses a different path. Sister 1, after seeing  humans killing themselves in endless wars all over the world, decides to help humanity, eliminate all wars, use her power to bring peace and prosperity to human beings. Sister 2 wants to become human, get married and have kids. Sister 3 wants to know their origin, their parents, where they came from, and understand the purpose of life. That is the moment the sisters separate.