While Jon and Janey travel to New Jersey - Jon to visit university friends and Janey to visit her mother - they pass by an amusement park. A photographer, mistaking the two for lovers, takes a picture of them. Janey's watch then breaks and Jon, being the son of a watchmaker, promises to repair it. At his hotel room, they make love for the first time.
A month later, Janey witnesses the incident in which Jon was accidentally locked in the Intrinsic Field Test Chamber before an experiment, intending to pick up Janey's watch that he'd left in his lab coat. He is disintegrated and a token funeral service is held. Janey places the photograph of her and Jon at the amusement park behind glass at the Bestiary.
When Jon returns as Dr. Manhattan, they resume their relationship. They spend that Christmas together, and Jon tells her that he will always want her, knowing full well of their relationship's doomed fate.
She leaves him when she discovers that a relationship had been building between him and Laurie, throwing down the earrings he had given her. It is revealed that Jon's disinterest in Janey was simply due to her beginning to grow too old for him, as he had ceased aging many years ago.
After breaking up, Slater started smoking 3 packages a day and caught recurring bronchitis, however her insurance wouldn't cover it as a pre-existing condition.
Due to her past association with Jon, Adrian Veidt takes her in at Dimensional Developments to work as a physicist, and as part of his long-term underlying plot, has her unwittingly exposed to radiation, contracting cancer along with many other of Jon's acquaintances.
Veidt pretended to offer to help her health, and find holistic treatments outside the U.S. He provided her with "medicinal" cigarettes, which however cause her lung cancer.
Jon takes their photograph from behind the glass with him to Mars, seemingly tattering it slightly when he allows it to fall from his hands and onto Mars' surface.