Thera was the personality stamped onto Maj. Samantha Carter on the planet P3R-118. (4.10 "Beneath the Surface")
Thera was very good with numbers. She also had a talent for mechanics, something which might have been programmed into her via the personality stamp. It is also possible that her expertise was taken from Carter's own skills.
Thera was much more open about her feelings than Carter. She didn't hold back in prodding Jonah (Jack O'Neill) concerning his feelings for her. For a while, she seemed content to be with him, even though her ideas about improving the plant were dismissed by her supervisor, Brenna.
One of the purposes of the personality stamp was to give the underground workers a sense of duty and to promote their being happy and honored to serve their people, whom they believed were living underground to survive an ice age. These underground workers were not aware of the domed city they were sustaining through their efforts.
Even though it appeared that the personality stamps were meant to make the underground workers happy and satisfied with their work, it didn't prevent bad feelings among them. Kegan, the woman who served the workers their meals, along with other duties, openly disliked Thera. When Kegan refused to serve Thera bread, something which evidently had happened before, Jonah grabbed her arm and demanded that she serve Thera. Carlin (Daniel Jackson) came to Kegan's defense and the two men got into a fight. This fight prompted Teal'c to remember who he was and to tell Jack and Daniel that they were friends and part of a team called SG-1. He even declared that they should escape from the plant. Jonah denied knowing Teal'c, whose stamped personality's name was Tor, but this incident only sparked Carlin's curiousity and led him to doubt who he was and what he was doing there.
When a pressure overload occurred which threatened her section of the plant, Thera acted quickly in shutting down the power directed to the boilers. Her actions, along with those of Jonah and Carlin (Daniel Jackson), were recognized by Brenna. Thera, however, was angered by Brenna's praise, letting her know that there would most likely be similar accidents if they didn't do some of the improvements she had proposed.
Jonah encouraged Thera to work with Brenna to get her ideas recognized and perhaps realized, but he spent most of his effort watching her from afar. It wasn't until Carlin told them that something was wrong and continued to prod them that Jonah and Thera began to spend their lights-out time together. This was against the rules and often meant denial of rations if caught. Based on this, Thera had a strong sense of duty and following the rules until it was deemed by Jonah to be okay to break them.
During their time together, Thera and Jonah cuddled. They expressed feelings for each other, thinking that this was something of their real identities. Jonah said that he remembered feeling feelings for her and she was happy with that revelation. When Brenna finally revealed her identity to her, Carter realized that any romantic feelings shared between herself and Jack were not appropriate because of their military positions and status on SG-1. Before leaving for home, they both recognized each other as "Carter" and "Sir". (4.10 "Beneath the Surface")
--DeeKayP 19:22, 13 Jun 2005 (PDT)