Power Hungry - S1-E5
Visible crew/equipment: When they're transporting Joseph Meegar out of the building and into the ambulance, you can see the reflection of the boom mike on the open car door, (the car Charlie is putting Mr. Fischer into). (00:41:00)
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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