User blog comment:JoePlay/Wizarding World Giveaway/@comment-4157745-20110717043644

Third, the connection between Harry and Voldemort's wands are finally explained. We already know that they shared the twin cores; therefore, they were already strongly bonded. However, the night at the graveyard, their bond greatened. Because Harry had more courage than Voldemort that night, his wand overpowered Voldemort's, and something very strange happened. The wands echoed their master's strong relationship, and a little piece of Voldemort himself actually embedded itself into Harry's wand. That is why Harry's wand outperformed Voldemort's wand in the beginning of book seven- even though Voldemort was using a borrowed wand which he thought would solve the twin core problem, Harry's wand dominated because it actually recognized Voldemort himself as the enemy.