We start the episode with a standard gimmick: Odo is concealed as an inanimate object to eavesdrop while Quark is some stolen goods. It's a quick scene, easy to figure out. That's web things go south, and one of the twinned Miridorn is killed. It seems that Quark had arranged for a robbery of the sale, as there's greater profit from hiring a thief than in buying the goods direct.
This sets up one of the themes for the episode, and of the series: family values, and Odo's search for others of his kind. When Odo brings Croden into custody, the prisoner reveals a key with shape-shifting properties, and promises to bring Odo to a planet with others of his kind.
There some interesting moments with Quark. When Ah-Kel confronts him to find out where Odo and Croden are, Quark once again uses his manual control rods to bypass the station's security systems. After Ah-Kel leaves, Quark notes that if he finds Croden, the vengeful Miradorn will learn that it was a planned robbery, and would then come after the Ferengi for their part in his brother's death. When Rom begins to despair, Quark then states that Odo would never give up his prisoner, and would die first, both preventing Quark's deception from being revealed, as well as removing Odo from the picture. Quark does not share Rom's enthusiasm at this possible outcome. This doesn't imply any shifting of position for Quark, but it does recognize his belief in Odo's character, as well as appreciating his role in the current situation. It seems that Quark likes the cat and mouse game he plays with Odo.
Beyond the Wormhole
We get another glimpse of the other side of the wormhole again, when the Federation attempts to contact Croden's home planet, to let them know that their former citizen was arrested for murder. The reasoning behind this move is questionable. In the episode Dax, they fight to keep Jadzia on the station, even holding a tribunal hearing to weigh the evidence. Of course, Jadzia is one of the main cast, while Croden is only in this episode. While Starfleet's starships get to cruise the galaxy in the Alpha Quadrant, Sisko gets to cruise through the wormhole on joyrides. It's exploration! On a more serious note, it's a way to see what's on the other side of the wormhole.
Again, it's hard to see what kind of reception Sisko expected, telling a planetary government that he's captured someone from the planet. Did he expect their undying thanks? Instead, it's a brusque demand that the prisoner be returned, to face their own justice. Reading between the lines of the dialogue, it's heavily implied to be the death penalty.
So, do you extradite prisoners to other nations when you know they're going to be executed? How much does the Federation value life, against potential trade with a newly discovered planetary system? Croden gets shipped off, under Odo's guard to Croden's home world.
Odo and Croden
Some clear parallels are drawn between Odo and Croden in this episode. Both are solitary, both are from the other side of the wormhole. Even their names are similar sounding. As often as Odo protests that he's nothing like Croden, it's clear that there are similarities.
It's interesting to watch Odo's attitude to Croden change from "criminal scum" to "I don't believe anything you say, but I'll go along anyway" to finally "you're a victim of unjust laws and circumstances and I'll let you go free into exile".
Again, this is mirrored by Croden's own change of heart after Odo is knocked unconscious on the asteroid. At first, he is ready to leave Odo to die, but then decides to haul him back to the runabout.
In the end, Croden's knowledge of the Vortex allows Odo to lure the Miradorn ship through the 'Vortex', a nebula much like that in The Wrath of Khan. The sequence, just as in the feature film, brings to mind submarine films more than space battles. The Miradorn vessel is destroyed, and Odo sends Croden and his daughter as refugees to Vulcan. Because in the Prime universe, Vulcan still exists.
Vortex first aired 18 April, 1993. Written by Sam Rolfe. Directed by Winrich Kolbe.