The Black Cavalry, Red Cavalry, and White Cavalry in Qing Yu's year were three different armies. The Black Knights were Chen Pingping's team. They were one of the Qing Kingdom's most mysterious and powerful cavalry forces. They were famous for their surprise attacks from thousands of miles away and had very powerful combat abilities. The Red Knights were the Qing Emperor's exclusive army. They were in charge of the Qing Emperor's safety and the Jingdou garrison. Their warhorses and soldiers were donned in red armor and looked awe-inspiring. As for the White Knights, there was no relevant information in the search results provided, so there was no way to know the specific situation of the White Knights.
There's no official rule saying they can't. Since fanfiction is a product of fan creativity and is usually not part of the official franchise control. So, they can probably watch it if they come across it.
Some popular ones could be 'Sword of the Rohan' which is known for its epic battles and complex characters. Another might be 'Rohan's Quest', a story full of mystery and adventure.
There could be multiple factors. His role models, whether they were his teachers, older siblings, or people he read about in books, might have inspired him. Also, the realization that hard work brings rewards, like good grades, praise from others, and a sense of accomplishment, would have made him keep up his hardworking attitude.
Popular 'rohan x josuke fanfic' often focus on their unique dynamic. They might play up Rohan's eccentricity and Josuke's more straightforward nature. Also, a lot of them involve some sort of mystery or adventure that the two characters embark on together.
It could be about a conspiracy within the Rohan setting. Maybe it involves political intrigue among the Rohan characters, like a plot to overthrow the king or some secret alliance that goes against the common good in the Rohan realm.
Rohan was a boy who always put in great effort in everything he did. He woke up early every morning to study before school. He was dedicated to his schoolwork, always completing his assignments on time and with high quality. He also helped his parents around the house, doing chores without being asked. His hard work paid off as he got excellent grades and was respected by his teachers and peers.
Some kamen riders could be amused. They may see the creativity of the fans in creating unique scenarios. However, they might also be a bit critical if the fanfiction strays too far from the essence of their characters.