In the Death Note story, there's this notebook that falls into Light's hands. He starts his 'cleansing' of the world by writing the names of wrongdoers. However, as he does this, the authorities, led by the brilliant L, start to suspect someone is behind these strange deaths. It's a complex story full of moral dilemmas as Light believes he is doing good, but his actions are still taking lives in a rather unethical way. There are also Shinigamis in the story, death gods who own the Death Notes.
The main characters are Light Yagami, a smart and ambitious student who gets the Death Note. And L, a world - famous detective who tries to stop Light. Also, Ryuk, the Shinigami who drops the Death Note into the human world.
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.
Oh, for sure! Death Note is considered a masterpiece in the manga world. Its unique concept and the way it unfolds make it a must-read. The characters' development and the moral dilemmas presented make it stand out from the crowd.