Liberty
After Michael gives himself up to Captain Windmark, he is taken to a secure facility on Liberty Island, where Windmark attempts to study Michael but finds the boy's mind impossible to read. He orders more invasive diagnostics to determine what Michael is. Discovering that the boy's intelligence exceeds that of the Observers while his emotional capacity exceeds that of standard humans, Windmark returns to 2609 to suggest to his superior that they destroy the child to protect themselves, but instead is told to simply "disassemble" the boy for future study.Broyles is able to learn of Michael's location and relays that to the Fringe team, but cautions them that the facility is nearly impossible to infiltrate. While brainstorming ideas, Olivia suggests that she be re-injected with Cortexiphan to let her cross over to the alternate universe, travel to Liberty Island there, cross back and retrieve Michael, and then repeat these steps to get back safely. However, Peter worries about the effects of re-dosing Olivia with potentially lethal levels of the drug, while Walter is concerned with the unknown condition of the alternate universe. Astrid suggests using the window ("Peter") to determine the state of the parallel universe, and through this, they find that there are no signs of the Observer invasion there, giving Olivia's plan credibility.
While September returns to the lab to start assembling the device to send Michael into the future, the Fringe team goes to an underground safehouse to prepare Olivia for crossing over. Walter administers four doses—one for each expected crossing—despite the harm it does to her medical condition. As the drug takes effect, Peter and Walter have a discussion about the nature of sacrifice. When Olivia recovers from the injections, Walter warns her of how long she has and that jumping too fast will cause rapid withdrawal symptoms.
Olivia jumps over near the site of the alternate-universe Fringe Division building, where she is met by her doppelganger and current leader of Fringe Division, Fauxlivia, and her former partner from the prime universe, Lincoln Lee; the two have since married and have a son. They arrange transport to Liberty Island and take her to the coordinates they believe Michael is being kept; Olivia crosses over but finds too late that the boy has been taken to surgery, while she herself starts experiencing double visions of the two universes. She fights her way through Observers, and stops the operation in time, with Michael smiling at the sight of her. With the boy, Olivia crosses back over, where Fauxlivia and Lincoln help to stop an Observer that followed her back across. Olivia thanks them for their help and crosses back over at Battery Park with Michael.
In the conclusion, Windmark discovers that Broyles has relayed Michael's location to the Fringe team. Meanwhile, September has completed the device, but one component fails to work. He goes to December, and requests a favor.
Tropes
- Alternate History: The Observers never invaded the Alternate Universe, so their world is still free and thriving compared to the state of the main universe. Fridge Brilliance kicks in if you believe the theory that this is the universe the Observers came from and don't interfere here to allow their creation to happen.
- Back for the Finale: We get to see the Fauxlivia and Lincoln Lee for the first time since "Worlds Apart".
- Happily Married: Fauxlivia and Lincoln are married and have a son together.
