One great fanfiction could be 'The Adventures of Trevor and Sypha Beyond Castlevania'. It delves deeper into their relationship as they travel the land after the events in the game. They face new threats and their bond grows stronger.
The popularity comes from their interesting relationship. They are two very different characters, Trevor the tough fighter and Sypha the powerful mage. Fanfictions allow exploring how they interact and complement each other.
In novels, the Prince of Demons usually did not directly PK the Princess because the Princess was usually a character in a novel or anime that represented a specific country or power, while the Prince of Demons was another character that represented a different power or goal.
In some novels or anime, there might be a battle between a demon prince and a princess, but it was usually because of a conflict of interest or goals between the two parties, not because the princess herself had evil characteristics. Therefore, the plot of the Demon Prince vs. Princess might appear in specific novels or anime.
I'm not sure who Trevor Holt specifically is in this story without more context. It could be a fictional character created for a particular book, movie, or other form of media.
Well, it depends on how you define 'good'. Trevor Story has shown flashes of brilliance, but his consistency can be a bit up and down. However, when he's on his game, he can be a real force to be reckoned with.
As far as public knowledge goes, no. Trevor Noah has been occupied with things like touring for his stand - up comedy, his work in television and digital media. He may be interested in writing a novel in the future, but there are no signs of it at the moment. He might be more focused on his current platforms where he can reach a large audience and express his views on various topics, from politics to social issues.