Paul is the friend of James Carlson who built the bazooka with him.
Paul and his friend James Carlson were into World War II history and decided to build a bazooka to re-enact it. They built the bazooka to exact specifications, but when they tried to use it, it didn't fire like it was supposed to. James went to check on it and then it started working and fired a shell into James's chest.
Paul came to the hospital to check on James and was yelled at by James's wife, who hated their hobby. During their argument, Paul revealed that the shell hadn't detonated, meaning there was an active bomb in James's chest.
When the Bomb Squad arrived, Paul helped them by telling him everything he knew about the shell they had built.
He and James Carlson are best friends. They're both World War II enthusiasts and they often work together to re-enact.