Gwen Rehayem was the daughter of Xavier Rehayem. After she and her father moved into the house in the late 1800s, she was possesed by the Exmortis. She was killed by her father in an attempt to free her soul.
When Xavier moved into his house, he found several books relating to the Exmortis. After translating them, he began to notice changes in his daughter. She fell into a catatonic state, never speaking and never even looking at her father, keeping emotionless at all times. Eventually, the research and obsession made the Rehayems the perfect, helpless targets for the Exmortis, and innocent Gwen became the subject of violent possessions as the Exmortis continued to haunt the family. She even begged her father to save her, but Xavier was too frightened to do anything. Finally, Xavier stabbed her to death while she slept, hoping that it would free her from her torture, but all it did was cause her ghost to haunt the house. Mad with guilt, Xavier committed suicide and he joined her as a tortured ghost. The two of them try to keep the Hand of Repose from realizing who he really was and they help Joshua Hannay to stop the Exmortis. She is not seen in Exmortis 2, but she is mentioned in a book Xavier wrote and is joked by Vlaew at the end of the game.