Well, Naga Fiction could be a genre of stories that center around the concept of Nagas. It might cover a wide range of themes. For example, it could be about a hero's adventure in a land ruled by Nagas, or a love story between a human and a Naga. There could also be stories about the origin of Nagas and their place in the fictional cosmology.
The story of Tungkung Langit and Alunsina is a Philippine myth. Tungkung Langit was the god of the sky and Alunsina was the goddess of the sea. They were once husband and wife. However, Alunsina became jealous and suspicious. This led to a rift in their relationship. Eventually, Tungkung Langit drove Alunsina away. After her departure, Tungkung Langit was left alone in the sky, and he created the world as we know it today from his loneliness and longing for his lost love.
It really depends on personal preference. Some might prefer Naga for its unique elements, while others might lean towards comics for their wide range of stories and art styles.
The main events are the marriage of Tungkung Langit and Alunsina, Alunsina's jealousy, Tungkung Langit driving her away, and Tungkung Langit creating the world after she left.
I have no idea who the author of 'harry is a naga fanfic' is. There are so many fanfic writers out there, and without more information, it's impossible to determine the author.
I'm not sure specifically as I haven't read this particular 'harry is a naga fanfic'. It could be about a character named Harry who has an interest in Nagas. Nagas are often mythical serpent - like creatures in various mythologies, so perhaps it's about Harry's adventures related to Nagas, like encountering them, befriending them or getting involved in some sort of story where Nagas play a significant role.