There is a clear line between the two worlds, known as the Kingdom of Light and Kingdom of Darkness, they lived by rules and abide them in order to have peace, one of them is that, neither a person from the two worlds must fall inlove with each other for it will bring chaos to the two worlds, darkness and light must not meet. This is a work of fiction, everything is purely written from the writer's imaginative mind. Any similarities to other works is not intended. Disclaimer: The illustration isn't mine (c)to the owner