Theresa was a citizen of Silver Skalitz, where she was a mine worker, and later an inhabitant of the Rattay mill. She is an intelligent and strong-minded woman, and is considered very attractive by the men of Bohemia.
On the morning of 23 March 1403, she was sent by her father to collect some nails from Martin's forge. She chatted with Martin's son Henry, and asked if she would see him at the dance that evening. Henry, despite being romantically involved with Bianca, stared after Theresa as she left, and Martin dryly commented she was a "fine lass".
Only a few minutes later, the village was attacked by a Cuman army led by Markvart von Auliz and King Sigismund of Luxembourg himself. During the attack, hundreds of citizens were butchered, including Theresa's family, and the whole village was burned to the ground.
Initially, Theresa fled with Matthew and Fritz, but they are separated. She tries to hide in a haystack, but Zbyshek pushed her towards a group of Cumans, who attempted to rape her. Luckily, she was saved by Henry riding a stolen horse, who distracted the Cumans, giving Theresa a chance to escape - or she manages to fight them off as Henry rides past. Devastated by the loss of her family and friends, Theresa remained in Skalitz, waiting to die, sure she had nothing to live for.
However, a few days later, she found Henry, about to be killed by Runt and his cronies. With the timely intervention of Sir Robard and his Talmberg Guards, they chased the brutes away from the unconscious Henry. Theresa, as part of her Chrisitan duty, ensured that his parents were buried before taking Henry to her uncle's mill in Rattay, where she helped nurse him back to health, finding new purpose in her life.
She remains in Rattay with Peshek for the remainder of the game, and keeps house for him - cooking and cleaning. Although he is quite gruff and distant, she views him with obvious fondness. She is also a vital source of advice and information for Henry. She prompts him to ask the miller at Ledetchko about hiring Matthew and Fritz in A Friend In Need..., and can help Henry determine the best people for the jobs in Aquarius.
Over time, Henry begins to develop romantic feelings for Theresa, and can give her gifts and court her as part of the quest Courtship. First, the two enjoy a walk by the river, where they laugh about the pompous nature of the local gentry. Then, Henry invites her to dinner at the Broken Wheel Tavern, where the two enjoy a meal and dance, before they are interrupted by a drunk man who insults Henry and then attempts to assault Theresa, who fights him off. Henry intervenes and beats the man up, and Theresa tenderly attends to his wounds. The two walk back to the mill together, and after a bit of awkward small-talk on the stoop, Theresa kisses Henry firmly - much to his surprise.
Finally, Theresa invites Henry to play blind-mans bluff with her. At first Henry laughs, as its a children's game, but agrees to play with her. Shortly after, Theresa realizes the thunderstorm will ruin her laundry and so she and Henry run outside to get it, then go back to the barn to dry the clothes. She is startled by the thunderstorm, and when Henry comforts her, they kiss, before lying down on the nearby hay and making love. She leaves before Henry wakes up the next morning.
The gift-giving feature seems to be buggy, as it will detect what Henry has in his inventory to give as a gift, but will not remove the item once it has been given to Theresa.
- Dagger. Theresa is slightly bemused by this gift, while a confused Henry points out that it could come in handy if she is ever attacked again. Theresa is appreciative of his concern, but isn't sure a dagger will be much help against the Cumans.
- Jewellery. Theresa is touched by this sort of gift, sure that he spent too much on it. She playfully warns him not to buy her anything else, lest she become spoilt.
- Antlers. She does not like this, and tells Henry to take it away.
- Flowers. After Klara rejects the bouquet in Next to Godliness, Henry can give it to Theresa, who seems pleased.