A New Day in the Old Town - S2-E1
Trivia: The observer quickly crosses the street after the car crash in the beginning of the episode. (00:00:55)
Trivia: The story is set mainly in 1985. During a scene in the other universe, the observers are outside of a cinema which is showing Back to the Future - with Eric Stoltz as the star rather than Michael J Fox. Stoltz was originally hired to play Marty, but was fired after filming started and Fox was brought in to play the role of Marty.
Answer: In the time line of Season 4, William Bell is trying to destroy both universes to create a new one, and he needs Olivia to power the collapse. So he helped her escape. But the real question is, if not in search of Peter, why Olivia has to travel to the alternate universe to be captured and replaced?
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