Big, fat, stinky spoilers for the last episode in Season Six, please don't read if you haven't seen. Please leave a review!
He hadn't known what he was looking for until he found her. And even then he hadn't known why he had stopped searching. He just fought to protect her. For her.
Until he was Captain Williams, the best of the best, who she couldn't live without. Because he didn't want to leave her. Because he didn't want to leave her yet again. Because he didn't know it but he had left her far too many times to count.
And in the end she left him, left him because he wanted to protect her. But she came back for him this time. Because she remembered him. This time.
And so he watched a man he didn't know, (but did know, oh so well, because they had both lived for so long and hurt for so long) marry a woman he knew, (but knew better than he thought, and worse than he would have liked, his little girl and the mysterious woman from his past) and then one world ended and another began. Again.