Back in the house, David finds that, although he has been in his study many times, the boxes were actually never unpacked after the move. He realizes that he has dissociative identity disorder and Charlie is not imaginary at all: "Charlie" is David himself. Whenever "Charlie" would emerge, David would be in his study. He also finally recalls the New Year's Eve party the night before his wife's death. He had caught Alison making out with another guest. "Charlie" was created as a way to express David's rage so that he could murder his wife, something the docile David was too decent to do. Emily knew the entire time about her father's split personality but did not tell him because she was unsure which personality murdered her mother until "Charlie" killed Elizabeth.