Laas was a Changeling and one of the "hundred" that were sent by the Founders to gather information on the solids they encountered. Like the Founders, Laas had an established distrust of solids based on experience.
Life on Varala
Laas ended up on the planet Varala, home of the Varalans. In the Varalan language, "Laas" means "changeable"–a name Laas considered to be very unimaginative. Not long after Laas learned to assume humanoid form, he found a Varalan mate. The relationship did not last because the couple could not have children, something that was very important to the Varalan female. Laas was fascinated with humanoids for a while, but eventually came to find it limiting. Laas once assumed the form of a volg and migrated to the southern continent with a herd. When Laas returned with the herd the next summer, the herd's breeding grounds had been fenced off. Laas had been among the Varalans for some time, perhaps as long as two hundred years.
Laas left Varala as a space dwelling creature and eventually sensed the presence of Odo on a Template:ShipClass runabout–it was the first time Laas had met another changeling. Upon returning to Deep Space 9, Laas was placed under Odo's supervision. Odo taught Laas of life in the Great Link by linking with him. Laas said that being linked with Odo helped him understand how he was meant to exist. Odo tried to show Laas that not all 'solids' were as intolerant as the ones he had met. Laas had lived on Varala for 200 years prior to meeting Odo and thus learned to assume solid and humanoid form long before Odo had. Odo and Laas speculated that either Odo was sent out after he had been, or Odo had been adrift for a long time before he was discovered.
Laas often spoke his mind, and had no problem with being himself and changing form in the presence of others. Later on Deep Space 9's Promenade, Laas turned himself into fog, something that displeased several Klingons. The Klingons became angry and attacked Laas, and Laas killed one of the Klingons in self-defense. Laas was placed in a holding cell, and General Martok asked that Laas be turned over to the Klingons. Colonel Kira Nerys helped Laas to escape, believing that Odo wanted to join him in his search for the other ninety-eight changelings. Odo did meet with the escaped Laas on Koralis III where he wished Laas good luck on his search and returned to Kira on DS9. (DS9: "Chimera")
- Laas was played by J.G. Hertzler, credited as Garman Hertzler at his own request. Hertzler felt that this was necessary to separate the role from his recurring character of Martok. Other actors considered for the role included Jeffrey Combs and Andrew Robinson, but it was felt that those actors would be too recognizable. (Star Trek: Deep Space Nine Companion, pp. 656-657)
- Hertzler partially based Laas' distinctive way of speaking on William Shatner: "I wanted to find a way to keep this character sort of annoyingly judgmental, because of his politics. He felt that these humanoids were so far beneath him that it was like talking to dogs. His pro-environmentalist point of view, feeling that humanoids ruin things, seemed like almost a passionate adherence to the Prime Directive. And that reminded me of James Kirk. William Shatner has a theatrical way of delivering lines by taking breathing pauses and holding onto the ends of words. I thought, 'That would work for Laas.' So that's where the voice came from. It's me doing my best imitation of Laas doing William Shatner doing Kirk!" (Star Trek: Deep Space Nine Companion, p. 657)
- Episode writer René Echevarria has been unable to recall exactly why he called the character Laas, but he did note that "I wanted his name to be something really strange and unusual. Ira kept making fun of it. Whenever we would talk about the story, Ira would say, 'And then the Swedish guy comes in...' " (Star Trek: Deep Space Nine Companion, pp. 658)
- Hertzler came up with his own backstory for the name. He remarked, "Laas has these wonderful speeches that question the very foundation of the Federation, where people of all religious and racial backgrounds come together to live in peace and harmony. Basically he saying, 'Forget about it. It's not possible. It violates the laws of nature.' To me, his name was laws." (Star Trek: Deep Space Nine Companion, pp. 658)
- The script describes Laas' alternate form as a "spacefaring lifeform", its "body is smooth and cylindrical, and it propels itself with a pulsating motion. As it "swims" alongside the Runabout, we see that it's almost as big as the ship." 
- Presumably, when he linked with Odo, Laas became infected with the morphogenic virus Odo was unknowingly carrying at the time. The producers realized this, but did not have time to address it in an episode before the series ended. Ira Steven Behr expressed his regret at not being able to bring Laas back. He notes that "that has nothing to do with whether he was sick or not. I just liked the character." (Star Trek: Deep Space Nine Companion, pp. 658)
In the Deep Space Nine relaunch, Laas returned to the Great Link. He was often sent to speak to Odo when he took solid form, such as in Avatar, Book Two and Worlds of Star Trek: Deep Space Nine Volume 3.
Loading-screen tips shown on Star Trek Online mention that the Founders broke all ties to Laas, declaring all Alpha Quadrant Changelings "renegades"; Changelings (and Jem'Hadar) appear in the game as hostile NPCs.