No. 'Death Note' is a work of fiction. It is a popular Japanese manga and anime series created by Tsugumi Ohba and Takeshi Obata. The concept of a notebook that can cause someone's death by writing their name in it is a highly imaginative and fictional idea.
Since it's not a true story, but in the 'Death Note' work, the main themes include power and corruption. Light Yagami, who gets the Death Note, becomes corrupted by the power it gives him. He starts believing he can be a sort of 'god' and decides who lives and dies.
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.
The 'gay Death Note fanfic' is different as it often focuses on relationships and emotions in a way the original doesn't. The original is more about the cat - and - mouse game of justice and power. In the fanfic, there could be a lot of focus on how two male characters interact on an emotional and physical level. It might also change the pacing of the story. While the original had a fast - paced plot with new twists and turns related to the Death Note, the fanfic could slow down to explore the development of a relationship, with detailed descriptions of their first meetings, first kisses, and so on.
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.