We don't talk enough about the fact that Amelia Pond, s5 Amelia Pond, before the timeline is reset, isn't just a normal orphan. Her parents didn't die, didn't abandon her, and didn't send her away. They never existed in the first place.
And if her parents never existed, then Amelia cannot exist. She is a causal impossibility.
"People fall out of the world sometimes, but they always leave traces." A photograph. A face carved into an apple. Yes. Sure.
Now that's too big, surely.
But that's what she is. She is exactly the same as these things. A trace. An echo of something that could never be, never was, never could have been.
And the universe should never allow it. A whole person, that's just too much. She could not have continued to exist indefinitely, in normal circumstances, after her parents never existed.
Because the Doctor didn't just save her from things coming out of the crack in her wall. He saved her from going into it. And he didn't just save her from the threat of going into it simply because of its vicinity.
No, by arriving when he did, he interrupted a process that was probably already in motion. And then by arriving again only moments later on a cosmic relative timestream (too quickly for the process to complete) and yet in the local relative timestream, years later --- years of a potential future caught midway through the process of rewriting -- he solidified that existence. Amy is a creature from another timeline, caught in amber. The Doctor prevented her from never existing, but only after she could already never exist.
And so, no one around Amelia thinks about it. Neither does she. There's some kind of consciousness block, because if you thought about it, really thought about it, for two seconds you'd realize she cannot exist. And the human mind can't deal with that. So, to protect itself, everyone's brain simply slides off it before ever noticing. They just assume that her existence makes sense, and don't question it, and don't notice what they don't question, that is staring them in the face.
But of course, to some extent they do notice. They can't think it, but they notice subconsciously that there's something they can't think. They notice there's something wrong with her, something uncanny. And they don't like it, and they alienate her even more because of it.
"Does it ever bother you Pond that your life existence doesn't make any sense?"
