I'm not sure specifically as I haven't read it in detail. But generally, it might be about an old toymaker and his experiences in making toys, perhaps his relationship with the toys he creates or the children he makes the toys for.
I'm not sure which novel you're referring to because there are multiple versions and different sequels. If you can provide more information such as the title of the novel, author, edition, etc., I will try my best to answer your questions.
The Jason the Toymaker original story is quite dark. Jason, the toymaker, has this workshop where he makes toys that are not normal. He's not your typical friendly toymaker. His toys can be a bit menacing. For example, some of the toys seem to have a mind of their own and might cause harm. He uses his toys to draw in victims, often those who are naive and easily attracted to his unique toys. There are a lot of twists and turns in the story that keep you on the edge of your seat.
One key event is his gradual descent into madness. He started off normal but then became obsessed with making toys in a very particular, and often disturbing way.
Well, the origin of Jason the Toymaker has elements of mystery. He began as an ordinary craftsman in the toy - making business. However, over time, he got influenced by some unknown forces. His toys, which were once symbols of joy, now became vessels for his deranged ideas. He might have faced some kind of trauma in his past that warped his perception of toys and their purpose.
Celestial Bane was a popular xianxia novel by Xiao Ding. It was published on Qidian Chinese website and was very popular among readers. The story told the extraordinary life of an ordinary teenager, revealing the cruelty of the world and the reality that everything was treated as grass. On the Qidian Reading App, readers could read authentic books and listen to authentic audio. The male lead was a young man named Zhang Xiaofan. Although he was not very talented, he had a strong will and a strong sense of loyalty. The female lead was Lu Xueqi. She was a cold fairy with extremely high talent. Her loyalty to the sect exceeded her pursuit of love.
A possible way is to create a new plot where the two universes collide. For instance, a portal could open between Jason's world and the wizarding world. Harry and his friends could accidentally stumble into Jason's realm and have to find a way back. Along the way, they encounter Jason's toys which have different powers and abilities that they have to deal with.