Dakin is the leader of the boys. He is Hector’s and Irwin’s favourite. Posner loves him. Dakin is the most advanced of the boys – apart from Rudge he is the only one having sex. He understands the game which Irwin is teaching them to play with history.
Dakin uses sex to get what he wants – he manipulates both Hector and Irwin. He offers himself to Irwin as a reward or a thank you for helping him get his scholarship to Oxford.
He is manipulative in other ways too – it is Dakin who gets Hector reinstated at the school, by blackmailing the Head about his behaviour towards Fiona.
Dakin doesn’t really care about other people, for example his careless attitude to Posner, and the way that he talks about Fiona. His eventual career as a tax lawyer, or at least Mrs Lintott’s reaction to it, also suggests he is not a very moral person. Even though it is he who saves Hector’s job, he was actually quite relieved that Hector has been found out.