Season 3, Episode 10:
Roscoe Joyce, the elderly former-keyboardist of Violet Sedan Chair, is visited in his nursing home one night by his son, Bobby, who died more than twenty five years earlier. When the Fringe team investigates, they find evidence that September the Observer was involved with Bobby's visit, and suspect that September had actually brought Bobby forward in time from 1985 and then returned him. Because Roscoe is having trouble remembering what Bobby actually said, the team bring him back to Walter's lab to use some hypnotic suggestion to help him remember, though Walter has an ulterior motive: he is a huge fan of Roscoe and Violet Sedan Chair's music, and in the process of helping Roscoe remember, he gets to hear Roscoe play a bit of music. The two talk and become friends, and Walter shows off something he's been working on, a milk-based serum to help him regrow the parts of his brain that William Bell cut out. Roscoe remembers what Bobby told him: it was a message for Walter.
Meanwhile, the Observer goes about a very complicated scheme. He intervenes in a bank robbery, easily disabling the robbers and helping a young woman who needs her inhaler, then steals it when he leaves. After this, he meets with Walter and attempts to convey the consequences of travelling between universes: a few months after Peter came to the prime universe, he caught a firefly one evening, meaning that a young girl who was supposed to catch that same firefly stayed out later, so her father drove out to find her in a bad storm and accidentally killed a pedestrian. Walter is called back to the lab, but the Observer gives him a message first: "give him the keys and save the girl." When Walter returns to the lab, Roscoe tells him about how Bobby died as a result of a car accident, and Walter realises that Bobby was the pedestrian that the Observer told him about, who was killed as an indirect consequence of Walter's actions.
Olivia and Peter bring in the woman who was saved by the Observer. En route, the Observer crashes a car into the FBI convoy, causing the woman to have another asthma attack but without her inhaler. Olivia chases the Observer while Peter stays to help the woman. Walter, having heard the entire incident over the phone, drives out the the site of the accident. Peter wants to take Walter's car to pursue the Observer, and says to Walter "give me the keys and save the girl." Walter realises what the Observer has done: he's set up a situation in which Walter will have to let Peter go for the greater good. Despite his misgivings, Walter gives Peter the keys and he's able to catch up to the Observer on a rooftop. The Observer comments on the difficulty of being a father before shooting Peter with the stun gun. Meanwhile, Walter creates a makeshift inhaler and saves the young woman's life.
Back at the lab, Peter is having some asprin to help with the headache he got from being shot with the stun gun. Thinking it's milk, he swallows it down with Walter's brain serum and starts to have a seizure. Walter helps Olivia to save Peter's life, and in doing so he realises the point of the Observer's schemes: had Peter not taken the keys, he wouldn't have been shot by the Observer and wouldn't have taken the brain serum, which was flawed and would've killed Walter if he'd taken it. Because Peter is young, he wasn't killed instantly and was able to be saved, if Walter had been unable to let Peter go for the greater good, it would've been Walter who drank the brain serum and died. In a scene between the Observer and his superior, December, this theory is confirmed, and they comment that Walter will now be ready to let Peter go when the time comes.
- Accidental Misnaming: Poor Astrid. Now Roscoe calls her Kelly.
- Actor Allusion: It seems to me Christopher Lloyd was in another story where a teenager time traveled from 1985.
- Aura Vision: Walter's Cool Shades let him see Roscoe's aura to determine the degree of his hypnosis.
- Butterfly of Doom: or firefly in this case.
- Call-Back: The band Violet Sedan Chair was first mentioned by Walter in "Grey Matters". He refused to go to the hospital and instead asked Astrid to return to the lab to retrieve their debut album. In "Northwest Passage", Walter picks up his Seven Suns vinyl record by Violet Sedan Chair.
- Compelling Voice: Walter hypnotizing Roscoe.
- Continuity Nod: "You can't get there from here, and besides there's no place else to go." is a quote from Sheldon B. Kopp's book "If You Meet the Buddha on the Road, Kill Him: The Pilgrimage Of Psychotherapy Patients", which Walter sent to Olivia. We previously saw Peter pick up a Bazooka gum wrapper that said "You can't get there from here." in "Northwest Passage".
- Convulsive Seizures:
- Another TV seizure with eyes closed, pelvic thrusting, and irregular shaking, nothing like a true generalized tonic-clonic seizure.
- With all the benzodiazepines Walter keeps in the lab, you think he could have found something better for treating a seizure then magnesium sulfate. If the plan was intramuscular administration, midazolam would be preferred, but lorazepamm or diazepam also could have worked.
- Why administer the drug in the right leg? The medicine has to get the brain before it works, so an intramuscular injection in any muscle where you won't cause damage should work equally well.
- Fake Band: Violet Sedan Chair
- Fanboy: Walter around Roscoe Joyce
- Grow Old with Me: Peter and Olivia watch the couple at the nursing home.
- Secret Test: The observers watching Walter.
- Senior Sleep Cycle: Roscoe
WALTER: These were created by an old friend of mine, Doctor Jacoby from Washington State.
- Walter is dancing to "Mah Na Mah Na".
- Dr. Jacoby of Twin Peaks inspired Walter's Making a Spectacle of Yourself.
- Title Drop:OBSERVER: Later that summer, Peter caught a firefly. I could not have known he would do that or that because he did a young girl three miles away would not.
- Worst Aid: The 20 oz plastic bottle would not be able to deliver air with enough force to overcome the resistance in the airways of someone having an asthma attack. If you encounter someone having an asthma attack, you want to sit them up and keep them calm. If they don't have their inhaler, and none is available in an emergency kit, call for an ambulance.