I'm not aware of any particular author for a 'dark fall novel' as the name is quite general. There could be multiple novels with this title by different authors.
The 'dark fall novel' could potentially be about a personal journey of a character into darkness. It might explore themes like loss, despair, and the human condition. For example, the protagonist could experience a series of tragedies during the fall season, which leads them on a path of self - discovery in a very dark and challenging way. The fall could symbolize the decay of their previous life or beliefs, and the story could be about how they navigate through this new, dark reality.
It depends on your perspective. Some parts of the Pokemon manga have elements that could be seen as dark, like serious conflicts or character struggles.
Well, in the 'Fall of the Dark Brotherhood Story', it might tell of how the Dark Brotherhood, which is usually a secretive and often feared assassin - like organization in many fictional universes. Their fall could be due to a hero or a group of heroes who decided to take them on. Maybe they were getting too powerful and attracting too much unwanted attention, so various factions united against them. It could also be because of a schism within their own ranks, where different ideologies clashed and tore the organization apart from the inside.
In the manga, Goku does fall into hell as part of a complex and adventurous storyline. This event leads to many interesting developments and challenges for him.
I'm not sure specifically as it depends on the particular version of the 'Fall of the Dark Brotherhood Story'. But it could include leaders within the Dark Brotherhood and those who oppose them.