In 2369, Croden spoke out against the repressive government of his homeworld, who retaliated by killing his wives. After slitting the throats of the security officers responsible, Croden fled the planet with his daughter Yareth, whom he placed in stasis on an asteroid in the Chamra Vortex, while he escaped in a shuttlecraft.
Sometime later, Croden's damaged ship was discovered by a Klingon ship, three light years from the Gamma Quadrant entrance to the Bajoran wormhole, and he was given passage back to the Alpha Quadrant.
Upon arriving on the Bajoran space station Deep Space 9, Croden met with Ferengi businessman Quark, who asked for his help in conning the Miradorn twins Ah-Kel and Ro-Kel out of a valuable egg sculpture. Croden accepted, on the condition that Quark would supply him with a small ship that could take him back to the Gamma Quadrant.
When the time came, Croden interrupted Quark's meeting with the Miradorn and demanded the twins hand over the egg. Refusing to do as he said, Ro-Kel flipped a table at Croden, throwing him to the floor, before taking out his weapon and firing. The shot narrowly missed Croden, giving him the opportunity to return fire using his own weapon. Ro-Kel was killed instantly. Before the situation could escalate further, Constable Odo, who had shapeshifted into a glass on the table, re-took humanoid form and restrained Croden, allowing a security team to take him into custody.
While detained in a holding cell, Croden justified his actions, in that he had been defending himself against Ro-Kel and that he was sorry for "making things awkward" but that he had had no choice.
He later revealed he knew of more Changelings like Odo living in the Gamma Quadrant. He claimed to have once visited a colony of shapeshifters and showed Odo a shapeshifting locket he had been given, promising to tell the Constable more in exchange for food, though Odo believed he was lying.
After traveling to Croden's homeworld, Commander Benjamin Sisko informed Exarch Hadran of Croden's arrest and upcoming murder trial. Hadran, visibly angered upon hearing Croden's name, demanded he be returned to Rakhar immediately so he could face his punishment under their law. Though Sisko attempted to reason with Hadren, the commander knew he had to abide by the Prime Directive and subsequently agreed, later requesting his release from the Bajoran militia.
With confirmation that Croden was to return to his home planet, Sisko assigned Odo to escort him there in the runabout USS Ganges. With Croden handcuffed in the rear, Odo piloted the Ganges alongside a departing Rigelian freighter to mask the runabout's signature, in order to avoid a vengeful Ah-Kel, who had been scanning all ships leaving the station.
During the journey to Rakhar, Croden spoke of Odo's people in an attempt to strike up some sort of rapport with him. He also revealed to Odo the reason why he had left his homeworld, going into vivid detail of the night he had to kill the security officers who entered his home and killed his family, though Odo was skeptical his story was true.
Before they could speak further, their runabout came under fire from Ah-Kel, who had discovered the plan to return Croden to his planet and wanted revenge for the death of his brother. With the shields taking more and more damage from Ah-Kel's ship, Croden convinced Odo to release him from his restraints so he could assist in piloting the runabout.
Croden managed to successfully avoid Ah-Kel by entering the Chamra Vortex and landing the ship on the asteroid on which he claimed there was a colony of shapeshifters. However, unknown to Odo at the time, Croden had actually hidden his daughter here in stasis and had lied about his experiences with Changelings, with his locket actually being a key for the stasis unit. On learning the truth, Odo reluctantly agreed to help save his daughter and promised he would take her to safety when Croden handed himself in.
While the group was en route back to the Ganges, Ah-Kel detected their presence on the asteroid and began bombarding it from space, causing a cave-in which landed on top of Odo, knocking him unconscious. With his daughter in his arms, Croden hesitated at first, but lifted Odo to his feet and carried him back to the runabout.
Odo regained consciousness and, with Ah-Kel still on their tail, piloted the ship through a dense pocket of unstable Toh-maire gas. When Ah-Kel fired his photon torpedoes at the Starfleet vessel, Odo engaged full impulse, resulting in a massive explosion within the nebula, thereby permitting their escape.
Soon after, the Vulcan science vessel T'Vran detected the explosion in the nebula and offered their assistance to the Ganges. Grateful to him for having saved his life, Odo said he would tell the authorities that Croden had died in Ah-Kel's attack on the asteroid and requested the T'Vran escort both him and his daughter to Vulcan.
"You and I have a great deal in common, Changeling."
"We have nothing in common."
"We are both aliens here, the only ones of our kind. Each of us is alone, isolated, shut out. Others like us only exist in the Gamma Quadrant. I have always wondered why Changelings are so distrustful of other species."
- - Croden and Odo
"Well, that's too bad. I was hoping you'd feel sorry for me, seeing as we're the only two here from the other side of the passage."
"I feel nothing for you but contempt. You're a thief, and a killer, and who knows what else."
- - Croden and Odo
"They tolerate you, but you're not one of them. Being what you are, you can pour your square shape into a round hole, but you never really fit, do you? You're like my stone."
"I think I finally figured out what crime you were found guilty of on your world."
"You talked too much."
- - Croden and Odo
"I never was told, and to this day, I don't know. They broke into my home just before dawn, and before I had time to stop them, they had murdered both my wives. You see, on my world, the punishment for being an enemy of the people is the death of your family. I had no sophisticated weapon. Only a short, slaughter knife that I used for cutting the necks of fowl we would prepare for supper. Imagine my surprise when I discovered that the necks of the security officers were no more difficult to cut than the birds. Even the sound they made as the blade crossed their gullets were similar."
- - Croden, describing the death of his family
"You're going to have to get used to living in an alien society."
"Like you. But I know where my home is. And perhaps someday I'll be able to go back there. I hope this helps you to find where you came from."
- - Odo and Croden, on giving Odo his locket
Croden was played by actor Cliff DeYoung.
To describe the scene in which Croden is introduced, the script for "Vortex" stated, "At the far end of the bar, a figure wearing nondescript clothes sits, drinking alone (CRODEN). He wears a locket on a chain around his neck. Odo moves halfway toward him to his usual spot at the bar, deliberately makes eye contact with the alien who looks away. Odo already has him marked for suspicion." (Star Trek: Deep Space Nine Companion - A Series Guide and Script Library, )
Producer Ira Steven Behr compared Croden's character to that of "Smith" from the 1977 film Sleeping Dogs; "It's about a man who's living a mundane kind of life and there's political turmoil and the next thing he's a wanted terrorist – and he hasn't done anything." Behr recalled, "It's a wonderful little movie, and that's what we saw this guy as. Instead of being a criminal, he's a guy who woke up one day and doesn't know why, but he did something wrong on his planet and they're after him now and he has to kill some people to get away from there." (Captains' Logs Supplemental - The Unauthorized Guide to the New Trek Voyages, p. 50)
Author Keith R.A. DeCandido said of the character, "Cliff DeYoung does a nice job with Croden, who's chatty and vaguely charming and totally awful at being a master criminal (the whole thing starts because he really sucks at being a thief). I especially like that he spends the entire episode talking too much, and we eventually find out that he's on the outs with the government that killed most of his family because he couldn't keep his mouth shut."