A joint Federation/Bajoran/Cardassian science mission to establish a communications relay through the wormhole is complicated when a Bajoran vedek believes that success will cause a prophecy of doom to come true.
- Accidental Misnaming: The Cardassians are clearly used to the station being called "Terok Nor", leading to a slip of the tongue during a briefing. Fortunately, Sisko lets it slide.
- Adorkable: Ulani and Gilora admit on arrival they'd spent most of the trip to DS9 trying to think of what to say when they go there.
- Anywhere but Their Lips: Gilora, who spends the episode hitting on O'Brien (in the Cardassian way, of course), gives him a goodbye kiss on the cheek after he tells her that he's Happily Married.
- Brick Joke: Quark intends to welcome the Cardassian delegation with a few bottles of kanar that he had stashed away, until Dax tells him that it's gone bad. A few scenes later, Bashir mentions Morn coming to the infirmary with food poisoning from a bad glass of kanar. It was on the house, apparently.
- Chick Magnet: O'Brien thanks to a bit of "Cross-cultural misunderstanding."
- Tsundere: This trope is the way Cardassians flirt.
- Crazy-Prepared: Federation standard operating practice includes having a backup to their backup power supplies. Gilora questions this, but given what the average Starfleet ship goes through, it's pretty smart.
- Cross Cultural Kerfuffle: Miles thinks he and Gilora are trading bitter barbs with each other other out of mutual dislike; she's actually flirting with him fairly shamelessly and thinks he's reciprocating. This immediately gets awkward when she gets frustrated at him being a tease and overtly propositions him in the middle of what he thought was an argument.
- Fantastic Racism: Miles thinks this is what's going on, at first. Then it turns out it's not humans the Cardassian he's arguing with has problems with. It's not even entirely clear if her sexism is real, or just a convenient excuse to trade barbs with him (read: flirt).
- From a Certain Point of View: The prophecy comes true. Just not in the way Sisko and Kira expected.
- I'm a Doctor, Not a Placeholder: Ulani and Gilora are scientists, not diplomats.
- Is That a Threat?: When Yarka tells Sisko that allowing the Cardassian scientists to carry out their experiment will bring destruction, Sisko asks him if that's a threat. To Yarka, however, it's what has been prophesied.
- The Mole: Dejar is really an Obsidian Order agent, whose mission was to sabotage the project in order to demonstrate that Bajorans and Cardassians could not work together.
- Prophecy Twist: The Bajorans have a prophecy about these events: "When the river wakes, stirred once more to Janir's side, three vipers will return to their nest in the sky. When the vipers try to peer through the temple gates, a sword of stars will appear in the heavens. The temple will burn, and its gates shall be cast open." The Bajorans believe that the "vipers" are the 3 Cardassian scientists, and that their actions will destroy the wormhole. The prophecy actually refers to the 3 comet fragments. When they travel through the wormhole, Applied Phlebotinum leaks out of the fragments, forming a "subspace filament", which holds the wormhole open slightly, enabling subspace communication with the Gamma Quadrant. The prophecy was completely true, but there was no disaster, it was just misinterpreted.
- Slap-Slap-Kiss: As mentioned, this is SOP for Cardassians. Miles, being Miles, shuts it down before Stage 3.
- Teeth-Clenched Teamwork: Despite being their "colleague", Ulani and Gilora don't get along very well with Dejar and often react uncomfortably to her. It's because she's actually an Obsidian Order agent who is there to (without Ulani or Gilora's knowledge) sabotage the mission. When Gilora realizes what Dejar's done, she doesn't hesitate to speak up.
- Token Heroic Orc: Ulani and Gilora are pretty non-standard Cardassians. Polite, friendly, nervous, fond of foreign food.
- You Have Failed Me: Gilora hints that Dejar might face this when the Obsidian Order catches wind of her failure.