Rose/Bill
From what I've known of him, he's either running from his past or dealing with it on his own terms. When one of us pops up unexpectedly, it throws him off.
I honestly don't even know anymore, though "complicated" probably applies. I've spent so much time away from him that that life is starting to feel like some wild dream I had after watching sci-fi with the boys.
I did much the same. Oh, that's horrible. Does the Doctor know about the memory thing?