Sisko has a dinner party, at which Jadzia plays a tune on a musical instrument, despite insisting that neither she nor any of the Dax symbiont's previous hosts had any musical ability. Shortly afterward she begins having violent mood swings and experiencing strange visions. She, Sisko, and Dr. Bashir go to the Trill homeworld, but their efforts to discover what is happening to her are stymied by the doctors there.
- Bunny-Ears Lawyer: Timor, the guardian of the symbionts, is extremely good at his job but comes across as Cloud Cuckoolander otherwise.
- Canon Discontinuity: Getting hijacked by Verad apparently doesn't merit as a "Traumatic event" for the Dax Symbiont.
- Desk Sweep of Rage: Jadzia takes out everyone on the chess boardnote when she suddenly gets angry at Sisko.
- Didn't See That Coming: Nobody expected someone as psychologically unstable as Joran to be able to bond with a Symbiont.
- Earworm: The melody that Jadzia plays during The Teaser. And like any good earworm, she makes sure it sticks in Sisko's mind as well.
- Faking Another Person's Illness: The Symbiosis Commission altered Torias Dax's medical record to report he was in a coma for six months before the Dax symbiont was transferred to Curzon, in order to cover up the six months that Joran Dax existed.
- Government Conspiracy: The Trill Government and the Symbiosis Commission have been lying for centuries about the relationship between the symbionts and the Trill species. The truth is that nearly half of all Trill are capable of being a host, but with so few symbionts the government invented the "only 1 in 1,000" lie to prevent symbionts from turning into commodities to be bought by the highest bidder or fought over as prizes.
- Laser-Guided Amnesia: The Symbiosis Commission implanted a "memory block" in Dax to prevent memories of Joran from surfacing. The issue is that the block is deteriorating, causing bits of his memories and personality to leak out.
- Leitmotif: The melody Jadzia plays in the cold open becomes Joran's theme for his subsequent appearances in the series.
- Malevolent Masked Man: Jadzia has recurring hallucinations of one. It's her memories of being Joran trying to resurface.
- Screw the Rules, I'm Doing What's Right!: Sisko doesn't care much about Trill politics, but he will save Jadzia's life, even if he has to effectively blackmail the Symbiosis Commission to do it.
- Sherlock Scan: Timor can tell that something's wrong with Jadzia at a glance, and figures out the rest by simply laying a hand on the implanted Dax Symbiont.
- Supreme Chef: The episode opens to the Siskos preparing a meal for the senior staff, with Ben stating that he learned all about cooking from his father, a successful restaurateur.
- Took a Level in Jerkass: Jadzia early in the episode. It's the first sign that something is seriously wrong.
- Unperson: The Trill government tries to purge all mention of Joran from their records and Dax's memory, causing the problem in the first place.
- Well-Intentioned Extremist: The Symbiosis Commission have to deceive the public about the percentage of join-worthy Trill to keep the Symbiont species from becoming nothing but a commodity.