Fringe, Season 4

Peter:
I have tried everything that I can think of, everything that I know how to do to get back home, and none of it has worked. Nobody here can help me, but you can. I know you can. Please help me get back home.

September:
You have been home all along.

Peter:
I don't understand. I was erased.

September:
There is no scientific explanation, but I have a theory. Based on an uniquely human principle, I believe you could not be fully erased because the people who care about you would not let you go, and you would not let them go. I believe you call it love.

Peter:
And Olivia?

September:
She is your Olivia.