The main characters are Light Yagami and L. Light is the one who gets the Death Note and starts using it to kill criminals. L is the detective who tries to stop him.
Ryuk would probably just be amused. He is a Shinigami who has seen a lot in his existence. Fanfiction is just another strange human creation to him. He might chuckle at some of the more outlandish ideas in the fanfictions, like a character having superpowers beyond the Death Note.
Misa would likely be excited. She is a big fan of Light and the whole 'Kira' concept. In fanfiction, if there are scenarios where she has more power or a closer relationship with Light, she would be all for it. However, she might also get jealous if there are other female characters getting too close to Light in the fanfictions.
The real Death Note story is quite complex. Light Yagami discovers the Death Note and begins his crusade against criminals. He quickly becomes a sort of self - appointed judge, jury, and executioner. As he kills more and more people, his sense of morality becomes warped. L enters the picture and starts his investigation. L is a very unique character, with his odd habits like sitting in a crouched position. Their struggle is not just a physical one but also a mental and moral one. Light has to constantly come up with new ways to avoid detection by L, and L has to find ways to prove that Light is the one using the Death Note. It's a story full of suspense, moral dilemmas, and psychological battles.
It was mainly inspired by the creator's imagination. The concept of having power over life and death in such a unique way makes for a very interesting and dark story idea.
Mello is quite an interesting character. His determination and his somewhat unorthodox methods make him stand out. He is willing to take risks and use his intelligence in creative ways to achieve his goals related to the Death Note.
Light Yagami is a main character. He is a brilliant student who discovers the Death Note and begins to use it to create what he believes is a better world by eliminating criminals.
There is no true story behind 'Death Note'. It was created as a work of art in the form of manga and anime. The story contains many fantastical elements such as the Shinigami, or death gods, who drop the Death Note into the human world. This is all part of the fictional universe that was carefully crafted by the author, not something that has any basis in reality.