Paul Marshall, Leon Tallis's friend and successful businessman, is the chocolate guy. He's also a doofus and a bore. When he visits the Tallises' home, he babbles on about his Amo chocolate bars that are going to be bought by the government to be shipped to soldiers. He even seems to want there to be a war just so he can make some money. When the nine-year-olds, Pierrot and Jackson, suggest that there won't be any fighting, Paul's spiteful enough to refuse to give them candy bars. It's like he's nine himself. Cecilia, on meeting him for the first time, thinks "how deliciously self-destructive it would be, almost erotic, to be married to a man so nearly handsome, so hugely rich, so unfathomably stupid" (1.4.36).
Paul's not just a doofus, though. He's also a villain. He assaults Lola—who is only fifteen. When she escapes him, he seeks her out again, and manages to rape her outside in the dark while the rest of the family is looking for the runaway twins. Quick reminder in case you'd forgotten: the twins are Lola's little brothers. And their parents are getting divorced. So not only does Paul Marshall rape Lola, but he does so while she's out looking for her missing baby brothers while visiting her aunt and uncle because her parents are getting divorced. He then sits back and lets Robbie take the blame. Paul Marshall is all kinds of yucky.
Eventually, Paul marries Lola, and goes on to be hugely rich and respected. He gets his war, he gets his money, he gets the girl, he gets away with rape. If anyone wins the novel, it's him. The doofus triumphs. Sometimes life is like that.