Gemma Scout

Gemma Scout is a fictional character on the Apple TV+ series Severance. She is portrayed by Dichen Lachman.
Though Gemma is said to have died before Mark begins work at Lumon, she is present on the severed floor as the Lumon wellness counselor Ms. Casey. Her loss is a major motivator for her husband Mark Scout to begin his job at Lumon Industries.
Gemma was a Russian literature professor employed at Ganz College. She married fellow university professor Mark Scout, whom she met at a Lumon blood drive. The couple was close to Mark's sister Devon and her husband Ricken Hale, who wanted to name their daughter after her, though Mark declined.
After Gemma suffered a miscarriage, she and Mark visited the Butzemann Fertility Center run by Lumon, where she signed up for IVF treatments that ultimately proved unsuccessful as well. Sometime later, Lumon faked Gemma's death, while secretly turning her into a test subject for their experiments with the severance technology. Unable to bear the grief of Gemma's loss, Mark decided to quit his teaching job, taking a severed job at Lumon.
Gemma is a subject on the testing floor of the Lumon headquarters, where she has been held captive for two years. She retains her memories and is sent each day to different rooms (whose names correspond to Macrodata Refinement [MDR] files), each of which creates a different innie made to endure unpleasant experiences such as a dental appointment or airplane turbulence. Her sessions in these rooms are overseen by the lecherous Dr. Mauer, who acts out different roles in each of the rooms and interviews Gemma afterwards to check whether she has retained any memories from the experiences. Gemma's inpatient care, meanwhile, is handled by her nurse, Cecily, and her ward contains a music player and copies of her favorite Russian literature. She is sometimes sent up to the severed floor where she becomes a part-time innie known as Ms. Casey, who serves as Lumon's wellness counselor for other severed employees. She interacts on several occasions with her husband Mark, though neither recognize each other, as both are severed. At the end of season 1 she is removed from her position as a wellness counselor and sent back down to the testing floor indefinitely.
During the use of the overtime contingency, Mark's innie learns that Ms. Casey is his wife after finding a photo from his outie's wedding to Gemma in Devon's home. When he returns to the severed floor, he resolves to find and rescue her, but finds that the wellness room has been decommissioned. Mark's latest macrodata file is called "Cold Harbor", whose corresponding room on the testing floor is the one room Gemma has not yet visited. Gemma asks Mauer whether she will be allowed to see Mark again after visiting all the rooms, but Mauer does not provide a clear answer. Mauer later lies to Gemma that Mark has remarried and fathered a daughter, and suggests that she too may have "moved on" while in one of the testing rooms. Gemma knocks Mauer unconscious with a chair and steals his keycard in an attempt to escape via the elevator, but upon arriving on the severed floor, she turns into Ms. Casey, whom Milchick simply ushers back into the elevator, keeping Gemma trapped on the testing floor.
In the season 2 finale, Mark and his innie learn that the numbers MDR refines are actually being used to create a new identity for Gemma every time a new innie of hers is created. Mark realizes that completing the 25th file, titled "Cold Harbor", will unlock a new innie for Gemma and that Lumon plans to test the new innie and kill her once the test has been completed. After Mark's innie completes "Cold Harbor", he rushes to save Gemma using security guard Mr. Drummond to get down the testing floor. After turning into his outie, Mark accidently shoots Drummond and uses his body to hold open the elevator and his blood to enter into the "Cold Harbor" room. There, he rescues Gemma. The two embrace for a moment before rushing to the elevator and going to the severed floor. Mark's innie leads Ms. Casey to the exit stairwell, where she leaves and reverts back to Gemma. Gemma begs Mark to leave with her, but Marks's innie chooses to stay on the severed floor with his newfound love Helly R. leaving Gemma distraught.
Series creator Dan Erickson described Gemma as "the hardest character to write," saying "We tried a lot of different things with her. The writing and the crafting of her character continued well into after we had hired Dichen, because we knew that this character was going to turn out to be Mark's wife. At one point it was like, well maybe it's Helly. But that felt, it's like too obvious. Like someone will guess that. And so we wanted this character that we could really hide in plain sight, where she would make sense as just an interesting kind of strange part of, piece of the Lumon furniture. And she would be somebody where we're not looking for what's the twist with her, because she sort of feels self-contained on her own."
According to Erickson the writers tried out a variety of character ideas for Mark's wife on the severed floor; for a long time they developed her as a traveling vendor who sold office supplies to the different departments, similar to an old west peddler in the style of a prospector. This idea was discarded as it was "too weird."
Reviewers noted how Ms. Casey's behavior on the severed floor appeared mechanical and strange. Dhruv Sharma of Screen Rant described her personality as "robotic" and "one dimensional." Erin Qualey of Vulture wrote that the character "evoke[s] a very strange yet warm presence" and "she seems like she was pulled right off the assembly line at Westworld."
Qualey described the reveal of Mark's wife Gemma being present on the severed floor as Ms. Casey as an "emotional gut punch." Reviewer Mary Littlejohn of TV Fanatic wrote, "It undermines the whole throughline of Mark's grief — or, maybe in some way, makes it more tragic. Innie Mark has access to Gemma, but he doesn't recognize her — he doesn't even know he was ever married."