He dug with a kind of fury, relishing the manual work, glorying in the non-magic of it, for every drop of his sweat and every blister felt like a gift to the elf who had saved their lives. His scar burned, but he was master of the pain, he felt it, yet was apart from it. He had learned control at last, learned to shut his mind to Voldemort, the very thing Dumbledore had wanted him to learn from Snape. Just as Voldemort had not been able to possess Harry while Harry was consumed with grief for Sirius, so his thoughts could not penetrate Harry now while he mourned Dobby. Grief, it seemed, drove Voldemort out…though Dumbledore, of course, would have said that it was love.
Harry Potter and the Deathly Hallows - J.K. Rowling