Complete story — includes the ending
In the parallel universe, Olivia manages to escape "Walternate" ' s clutches and takes taxi driver Henry ( Andre Royo ) hostage to get around New York. Throughout Olivia's attempted escape, it is revealed that the experiment was an attempt to replace her memories with those of her alternate counterpart. Olivia remembers a safe house and decides to go there. It turns out to be the home of her counterpart's mother, Marilyn, ( Amy Madigan ); Olivia's real mother died years ago. Marilyn convinces Olivia that she suffered a mental breakdown as the treatment takes full effect. Now that the experiment has succeeded, she "returns" to Fringe Division. Meanwhile in the prime universe, Walter and Peter prepare to move on with their lives, with neither seeming to suspect that the Olivia with them is in fact her alternate counterpart in disguise.
Sources and content license
Source and revision history · Adapted from Wikipedia contributors, Fringe season 3. HTML formatting and reference markers removed. · Content license