Odo has found the home planet of his people, yet something doesn't feel right. He's having difficulty connecting with them, can't help but notice their xenophobia toward "solids," and becomes increasingly certain they're hiding a secret from him. Meanwhile, the crew of the Defiant is rescued after their Gamma Quadrant mission and returned to Deep Space Nine. There they meet shocking news: the Dominion has made overtures of peace with the Federation. But this too doesn't feel right. The Federation seems too eager to agree to the Dominion's increasingly difficult demands: to break an accord with the Romulans, give up control of Deep Space Nine, and abandon the Bajorans.
There's a bait-and-switch in this episode that reportedly annoyed many viewers when it first aired: everything that happens on the station is really part of a simulation in the minds of the characters. Or, uncharitably: "it's all a dream." I side with the writers and their intentions here; the episode shows just how powerful the Dominion is to toy with the heroes like this. Cunning too. As writer Robert Hewitt Wolf put it, "the whole thing was a test" for them -- if they can take over the Federation slowly, by diplomacy, why expend military resources?
Even if this part of the story is fake, interesting things still happen. We see Sisko stick up for his team, charging in to yell at a superior officer over Dax's transfer. We see him and his officers take a firm moral stance, choosing insubordination over blindly following bad orders. We can also infer the cleverness of the Dominion in how complete the scenario is... it pushes the test subjects one way with a stonewalling Admiral Nechayev, pulls them another with a supportive Garak, draws out their feelings with a questioning Jake, and mocks them with a self-righteous Quark.
But you don't just have to infer; you learn even more about the Dominion from what the Founders come straight out and say. The Changeling Leader that interacts with Odo tells a story of how her people were once hunted and tormented by "solids," leading to their xenophobia. We never learn the actual historical truth in the series, but it's probably not as white as she paints, nor as black as the changelings being maniacal subjugators without provocation. In any case, their attitudes are so deeply entrenched that Odo's interactions with them changes nothing -- not his memories (shared via "link"), and not seeing firsthand how caring and true a friend Kira is to Odo.
Odo may have finally found "his people," but the episode repeatedly shows how little he has in common with them. He has no instinct to explore other shapes in the arboretum, as the Leader suggests. When he tries it, it means nothing to him. Most profoundly, the Founders have no sense of justice as Odo recognizes it -- the core of his being is absent in theirs. The conflict is well-defined right out of the gate, this episode serving to develop the Founders as clearly as the second season finale set up the Jem'Hadar. (Notably, though, the writers still haven't quite figured out what to do with the Vorta. After this, we wouldn't see them again until nearly the end of season four -- when Jeffrey Combs' performance as Weyoun would blaze the trail.)
- Jonathan Frakes directs his first episode of Deep Space Nine, with his signature use of high, wide angles to put characters in isolation. He spoke glowingly of this experience, noting that an Odo story "was like having a Next Generation episode assignment to direct a Data story." Besides praising the work of Rene Auberjonois, he also loved the spacious Deep Space Nine sets, saying "it's hard to find a bad angle on that space station."
- In a nice bit of continuity, the monolith seen in the changeling arboretum matches the one in seen in "The Alternate," that was claimed to be a "relic of Odo's people."
- The Vorta character of Borath was originally planned to be Eris, the same character from "The Jem'Hadar," but actress Molly Hagan was unavailable to reprise the role. Her loss perhaps was ultimately Jeffrey Combs' gain.
- "No changeling has ever harmed another" is a huge bell placed in this episode that you know will someday be rung. It also further underscores the Founders' xenophobia, as the idea of killing each other is so unthinkable, while the idea of killing solids is so unworthy of thought.