Very interesting scenario for Ubik's past. You managed to make a tale for Ubik where he is an artist with quitr a religious background & someone who is a master storyteller. I would however changes the rich family background slightly. Maybe something like along the line of him from a mysterious broken noble house who suffered from war, then he was send as an orphan for protection into Holy See church orphanage. This would add more layers to his character, someone who already experienced a lot since being a child.