Something else had clicked for him, something else that had never made much sense, but he had no other proper explanation for. When he'd brought it in the days following her arrival in New York from the Carpathia after the Titanic went down, she hadn't known what he was talking about. At the time, he attributed it to stress, the trauma of having nearly gone down with the ship -- or assumed that there was something more to that multi-headed cave shark that equaled secrecy and a non-discussion clause she hadn't bothered to inform him of, but it didn't add up.
Unless...
"That was you, wasn't it? Not you, but you. This you, the one that got stuck in the past and had to follow history up into the future. In 1912, I mentioned you having come to me ten years earlier about some stupid little cave shark, and you had no idea what I was referring to. That's why, isn't it. Because that wasn't you who did that, it was you."