Voldemort traversed Theodore's thoughts, verbally hissing at the sight of Dumbledore. It wasn't suspect that Theodore would meet with the Only One He Ever Feared, but it didn't mean Voldemort had to like it. Of course having a servant who could get that close to the Mudblood Lover could be useful. Reluctantly, he moved on.
Oh, I will take it. I will take it, and then I will make you watch as I use it to kill everyone you love, Harry, Voldemort thought in response to the challenge, letting his thought freely (and knowingly) travel to Theo's mind.
He watched as Theo's memories fluttered to other recent scenes. He could've pressed forward, breaking Theo's mental blocks, and seeing these scenes, but he really didn't care about how much this man missed his wife.
"You have not killed the man that stole your daughter's future?" Voldemort queried with an arched eyebrow and clear disappointment in his voice.