"The future is not the future anymore," Harry and Draco said as one, taking one another by surprise: Draco continued for both of them, "our very presence changes everything. For us to be able to predict the future we’d have had to behave in exactly the same way as we did the first time round - I’m sure you can appreciate how impossible that is," Hermione nodded sagely, but Ron only frowned in concentration, "and we’d have had to do that for twenty years straight,"