The creation of the Death Note manga dates back to 2003. It has since become a cult classic in the manga world, known for its suspense and intellectual depth.
A 'Death Note Love Story' could be centered around two characters who are on opposite sides of the fight over the Death Note. One might be a Kira supporter and the other against Kira. Their love could develop as they see different aspects of each other through their battles. It could show how love can grow even in a world filled with death and power struggles brought about by the Death Note.
Misa Amane could also be a main character in a 'Death Note Love Story'. She was in love with Light in the original story. In this new story, her love for Light could be explored further, or she could find a new love interest. Maybe someone who tries to save her from the dark path she's on because of her connection to the Death Note and Light.
First, you should consider the respect for the original 'Death Note' story. Even in fanfiction, the essence of the characters like Light's intelligence and L's deductive skills should not be completely distorted. Second, be aware of the rating and content warnings. Since it's 'lemon' which might imply some more mature content, make sure it's something you're comfortable with.