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.
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.
The Immortal Ancestor was Hongjun. The immortal ancestor in ancient mythology was Patriarch Hongjun. He was a character in the Investiture of the Gods and was considered the ancestor of all immortals. Patriarch Hongjun had three disciples, namely Sect Master Tongtian, Grand Supreme Elder, and Primordial Heaven Supreme. These three disciples were existences transformed from the three souls of Pangu when he was immortalized. Patriarch Hongjun was of the same generation as Nuwa and Fuxi. They were all respected gods from ancient times. They fused with the Heavenly Dao and achieved the status of a Saint. They depended on the Heavenly Dao and belonged to it. In short, the Immortal Ancestor was Hongjun.
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.