It's hard to say exactly how long the 'zzz' story is. Factors like the genre, the amount of detail, and the intended audience can all influence its length.
The 'rost back story' could be a fictional story too. It might involve elements like Rost's adventures in a fantasy world, his encounters with different characters, and how those experiences shaped him. However, without further information, all of these are just speculations.
Maybe if we knew where the term 'rost' came from, like a particular culture or a local legend, we could start to piece together the back story. For example, if it's from a Scandinavian - inspired story, Rost might have a back story related to Vikings, their values, and their way of life.
I recommend StarCraft: Dynasty of Steel, which is a novel about games and other worlds. The protagonist, Tang Feng, was a captain of the Earth Federation. He descended into the other world and possessed an auxiliary combat chip. He opened all the mechanical information of the military and fought with his younger brother, Tang Zheng, in the other world. The plot of this book was wonderful, and it included the collision of technology and magic. It was worth reading. I hope you like my recommendation, Mwah ~😗
Si Lili's younger brother was Li Lisi. Li Lisi was a descendant of the Qing royal family. Their lineage had been destroyed after the Qing Emperor ascended the throne, leaving only Si Lili and Li Lisi. In order to protect her brother's safety, Si Lili changed her identity and sneaked back to the Qing Kingdom to be a spy. However, the identity of the younger brother was not explicitly mentioned in the information provided. Therefore, it was impossible to determine who Si Lili's brother was.