Set during the road trip Claire and Peter took in S1.
Of course, the last thing he wanted to do was blow up half of New York (.07 of the population of the Earth, Nathan had told him the number, voice husky with meticulously locked-away guilt), but Nathan had already given up and Mom had already given up and he had already given up. Claire hadn't. Of course. As he drove along, tracking her every movement in the rearview mirror without ever actually looking directly at her, Peter knew she hadn't.
God, he was going to hell for these thoughts, for watching his niece like an uncle never should, for a tiny little part of him praying that Sylar (or, if it must be, him) would blow up. Because chances were Nathan and Heidi and Angela and Mr. Bennet and everyone who had ever known either one of them (and more importantly knew their connection and their blood) would be dead and they could forget and it would cease to be so wrong.
It scared him, beyond reality, beyond comprehension that he wanted to kill millions because there was a niggling feeling in the back of his throat when he looked at his fifteen year old niece.
Peter shifted the mirror and focused his eyes back on the road.