As mentioned when discussing Jonathan, Dio is the black to Jonathan's white—rather passive and perhaps a bit uninteresting as a main character. Joseph, on the other hand, is easier to perceive as being proactive, and I felt like that worked. As I wrote Joseph's tale, it was more as if he was in control of how the story progressed, so I think he ended up being more of an "adventurer," if you will. In comparison to the gentlemanly Jonathan, Joseph is constantly looking to win in confrontations or games and will do insane things without hesitation. In more crude terms, he has the personality of a swindler. This isn't only to create a contrast between him and Jonathan, but also because I wanted the focus to shift from the physical battles of Part 1 to more cerebral confrontations.
Back then, as an extension of my other work, Cool Shock B.T., I wanted to make Joseph a shonen manga character that bends the rules as he fights. Essentially, have him use the playbook of a swindler to win using cunning and logic. I also didn't want him to be the type of character who wins with bravery and perseverance, so it was easier to flesh out his personality with lines like "Your next line is…" where he ends up reading the actions of his opponent ahead of time. To put it simply, Joseph is more of a muscle-bound B.T. I put some Stallone into B.T. and added some cheerfulness for good measure to make him more of a jolly fellow.
Joseph is the character that connects the Joestar bloodline to Parts 3 and 4. I made Jonathan die for the storyline in Part 1, but I didn't even consider killing off Joseph. If I had known JoJo would go on until Part 8, I think I might have changed his visual design a little bit.
Q. Why does Joseph have a hat and goggles?A. To help differentiate him from Jonathan. Part 2 takes place when airplanes were first becoming prevalent. That's why I gave him a pilot's hat with goggles--sort of a steampunk or biker look.