It had to be someone who knew the gist of the prophecy, that only Harry could destroy Voldemort, and who had something to gain from Voldemort's defeat. Whoever was behind this, it was extremely resourceful of them to use someone else – Harry – to do all the dangerous work, to get rid of Voldemort for them, leaving them to reap the fruit of victory without having to make the effort or take the risks. It was a scheme of a cleverness that Hermione had to admire.