Culture and tradition
The Kreetassans were particularly concerned with proper etiquette, courtesy and adherence to certain, sometimes complex social codes. As a result, they came to have a reputation for being easily offended, and a number of such offenses occurred during problematic early encounters they had with Humans. (ENT: "Vox Sola", "A Night in Sickbay")
The Kreetassans considered eating a taboo to be performed privately, in the same manner as mating. (ENT: "Vox Sola") Also, when a ship was in orbit of Kreetassa, it was, as a courtesy, expected to align its chronometers with that of the Kreetassan capital city.
The Kreetassans revered a row of Alvera trees that stood in front of the Kreetassan Hall of Diplomacy and were, by 2152, over 300 years old. The Kreetassans considered these trees to be cultural treasures. Defacing them in any way was a major offense to their people; however, if it was done accidentally, there was a special, elaborate apologizing ceremony that involved cutting the tree into many pieces.
Kreetassans were a humanoid race who had an elaborate facial structure. They had heavily ridged faces with a row of purple-tinged rectangular scutes along the midline of the forehead (nose to hairline), covering one-third of its width. They wore their hair long and in braids, and dressed in long, brown, embellished gowns. (ENT: "Vox Sola", "A Night in Sickbay", "The Seventh")
After accidentally and unknowingly removing a symbiotic lifeform from its homeworld during their research, the Kreetassans, in about early 2152, paid a visit to Enterprise NX-01, making first contact with Humans then. However, the Kreetassans were offended when they saw the crew of Enterprise eating food in public, which caused them to storm off the ship in rage, very soon after arriving. They departed just as the organism was transferred to Enterprise and took over a cargo bay there. Shortly afterwards, the Kreetassans studied Enterprise's database and found learning the English language to be very easy. Their anger was alleviated when Travis Mayweather profusely apologized on behalf of Enterprise's entire crew and assured them that no insult was intended. After accepting the apology, the Kreetassans sent Enterprise coordinates of the organism's homeworld, allowing the lifeform to be returned there. (ENT: "Vox Sola")
In late 2152, Enterprise visited Kreetassa to make up for the political mishap a year earlier. They were invited down to the Hall of Diplomacy, and after sending the Kreetassans their genome, Captain Archer, Hoshi Sato, T'Pol, and Porthos (the captain's dog) went down to the planet. After the initial meetings went well, the Kreetassans were shocked and sent them back to Enterprise, for reasons the Enterprise crew couldn't comprehend. After asking the Kreetassans what had happened, T'Pol informed Captain Archer that Porthos had urinated on one of the sacred Alvera trees.
To apologize to the head of the Kreetassan government, the Enterprise crew asked that Archer perform a ritual. In a ringed area inside the Hall of Diplomacy, he would have to cut the tree's trunk on a special base with a chainsaw, and arrange the five-centimeter-thick rings in a special pattern (pictured right). Throughout the whole ceremony, he would wear beads in a special pattern in his hair and have Kreetassan markings on his chest in red ink. At the conclusion, he had to say a message in the Kreetassan language.
After the ceremony, the Kreetassans happily gave them the plasma injector they needed, and also an additional two spares. (ENT: "A Night in Sickbay") A Kreetassan merchant also recommended a mining colony as a source for deuterium. (ENT: "Marauders")
Communication and technology
In the final draft script of "Vox Sola", Kreetassans were simply referred to as "exotic-looking humanoids."
It was made clear to Costume Designer Robert Blackman that the Kreetassans should be "elaborately dressed." He based each Kreetassan character that appears in "Vox Sola", of whom there are three, on a particular set of colors and textures, also allowing for small variances from the ones he selected. Concept art for at least two of the three Kreetassan characters was also produced and was used in the ENT wardrobe department. (On the Set, ENT Season 1 DVD/Blu-ray special features)