Paolo is a real person. He's a boxer, an actor, and a politician, to name a few things, and he plays himself in the Swedish film adaptation of Fire. In this novel, he's also a friend of Salander's, though, of course, she doesn't even know it. How did they meet? Well, he taught her how to box when she was younger. In Fire, Paolo saves Mimmi from being chainsawed by Niedermann. He also discovers that Niedermann has a bizarre medical condition that prevents him from feeling any pain.