“World-build for an in-progress work, specifically for a magic system”
The main character’s parents have a door that goes anywhere. Through his childhood, the character didn’t know about this door, and he only found out about it by accident when he did. His parents are unhappy about him finding out. They didn’t want him to know because they didn’t want him to follow their footsteps and do what they did.
The door can go anywhere. The parents use this to gather scarce and special materials from all corners of the planet for special paintings that have magical properties. A portrait of a person with the right ingredients can improve their health or maybe their fertility. A different portrait can sabotage their health, or make the stressed or unlucky. Without the door, obtaining the right materials in the right purities would be nearly impossible, but it’s still quite hard as you must have been to the location before. The parents apprenticed to learn these locations and materials.
Naturally enough, there are people who use the paintings to control and harm people, and people who use the paintings to help and enrich people, and these two groups don’t like each other. The character’s parents are the nice group, but each group works hard to maintain the secrecy of their identity, since then the opposition could paint a portrait of them.
The paintings need not be only portraits. A painting of a volcano with the right ingredients might increase the likelihood of an eruption or a painting of a plane with the right ingredients might increase the likelihood of a smooth flight. A painting of locusts could either increase or decrease the likelihood of destruction by them.
The parents don’t want the character participating because the good side has been losing, and their own health has been sabotaged. The bad side has a sense of honor, and doesn’t generally attack unaffiliated people, but if the character were to become involved, his health and safety would be vulnerable.