It's completely fictional. The story was crafted by the author's imagination and not drawn from any true incidents. It's designed to entertain and engage the readers/viewers with a made-up plot and characters.
To some extent. 'Dance with Wolves' has roots in real history, but the story has been adapted and embellished to make it more cinematic and engaging for the audience.
It's not a true story. 'Dance with Devil' is a fictional tale that takes us into a made-up world. The plot and characters are all products of the author's imagination.