Walter Bishop has lived an interesting life. This is a photo of him from 1985, courtesy of the episode "Subject 13."
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We go back to the 80s on this episode of Fringe. You're looking at a photo of Walter from "Subject 13."
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On "Subject 13," Fringe viewers will get a look at Walter's past. There's a lot more to learn about this man.
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Fringe Season 3 Episode 15 Quotes

Walter: The texture of the universe has changed from my crossing. It cannot withstand any more damage.
Elizabeth: Neither can he, Walter. He is in constant distress.

Getting him back wasn't as easy as I thought.

Walter