Like, he would most likely live in Sharia at Rudy's house together with Zenith and Lilia. I can easily picture Paul being a doting grandpa to Lucy and his other grandchildren.
I'm curious to know what his reaction would be when he meets Rudy's friends, like Cliff, Zanoba, Linia, Pursena, and Nanahoshi. I'm also curious about his reaction when he finds out that Rudy is going to challenge Orsted to a death match and is building the Magic Armor, an imitation of the Fighting God Armor. Paul always thought that Rudy was a genius, so seeing his son work with two other geniuses (Zanoba and Cliff) to build the Magic Armor would probably come as both a surprise and yet not be surprising at the same time.
He would probably be surprised to learn that there are other people who can stand shoulder to shoulder with his genius son.
Also, what do you think his reaction would be when Rudy tells the family about working under Orsted, about Hitogami, and about Geese being Hitogami's last apostle and trying to kill his son, his son's wives, and his grandchildren?
Paul seems close to Geese, and I think he's the type of person who values friendship. But one of his close friends is now out for his family's blood.