Fringe, Season 4

Peter:
Walter, I know how strange this all is, how hard it must be for you, but I don't know what to do. Nobody remembers me here. Olivia looks at me like I'm a stranger; like she's afraid of me. I know what you're capable of. I need your help, Walter, to fix this.

Walter:
Every day for the past twenty-five years, I've tried to imagine what you would look like as a man, my son, but I don't deserve this. I don't deserve you. I realize now this is my punishment. You were sent to tempt me, to see if I would repeat the mistakes of the past. You shouldn't be here.

Peter:
Walter, no.

Walter:
Wherever you came from, however you got here, it doesn't matter. I can't help you.

Peter:
Walter, you don't understand.

Walter:
I tried to help a boy. A version of my son twenty-five years ago. That boy was never my son, and neither are you.