Being witness to Annie's reunion with her sister was most enjoyable thing Nathan had done in days, for his perspective at least. He hadn't been entirely certain Annie believed him when he'd gone to tell her, so he was glad her sister was in the lobby when Annie descended the stairs. He was still just a little worried about getting back on her bad side and being taken for a liar, however unintentional, would get him right back there, no doubt.
Behind the two, he watched the reunion with a wide smile, able to understand the young woman's emotions without any effort whatsoever. Being reunited with ones siblings was a feeling that really couldn't be matched, especially when worry and even fear had preceded it.
"Nathan Petrelli," he said, holding out his hand with that same smile in place, effortlessly warm. "And the simplest explanation is 'the Hyperion Hotel'. Peter should explain the rest."