Caduceus Database

Tyler Chase is a surgeon that works at Caduceus USA. He has a younger sister named Amy Chase, and is a long-term friend of Derek Stiles.


Tyler has long, unkempt blond hair and blue eyes. He is in his mid- to late-twenties, and is often shown smiling.

In Under the Knife, he wears a long-sleeved, light blue uniform with a small design of a bear on the left breast pocket. This was changed in Second Opinion so that he wears a short-sleeved coat over a dark shirt with slightly longer sleeves. The Caduceus symbol is placed over his right breast pocket. Tyler's design does not change from Second Opinion to Under the Knife 2.


Tyler is usually cheerful and optimistic. He is shown frequently cracking jokes with Derek and Amy, his sister, who he is fiercely protective of. He also teases Derek and Angie about liking each other.

In some respects, Tyler is lazy and doesn't want to work very hard. By Under the Knife 2, however, he has become remarkably more hardworking and is ready to spring into action on a moment's notice.

When Amy is being prepared for surgery and again during the HOA kidnappings, Tyler is shown visibly concerned for their well-being. He tries to keep people's best interests at heart.


Tyler and Derek went to med school together. Tyler did extremely well there, placing in the top five of the class. According to Derek, he was the professor's favorite student.

Two years prior to story events, his younger sister Amy became infected with Deftera and was hospitalized at Caduceus. This was what drew Tyler to work at the organization as well. He describes her condition as "payback" for his work in euthanasia.

Under the Knife/ Second Opinion

Derek meets Tyler shortly after transferring to Caduceus, and they express excitement about working together. Later, Derek discovers some research papers Tyler has written about euthanasia, and letters from family members who died at his hands. Tyler catches him and, by way of explanation, takes Derek to meet his sister Amy in the Recovery Ward. He does not believe she will ever recover, and it is revealed that he plans to euthanize her to end her suffering.

When Amy's condition worsens, Derek wants to operate on her, and Tyler shouts at him that it won't do any good. Amy overhears this conversation and pleads with them to do the operation, making Tyler realize he never took her feelings into consideration. He asks Derek to operate, saying that he "doesn't deserve" to do it. Derek performs the operation that cures her, saving her life. Although Tyler offers to let Derek turn him in, Derek disagrees, instead telling him to re-edit his thesis and submit it so he can help people.

Tyler is one of the people who completes at least part of Victor's puzzle, in order to work on designing a new laser to defeat Pempti. He will also help to treat the GUILT outbreak in the city. When Delphi breaks into Caduceus, he immediately volunteers to go after them, and says the women should stay in a safe area so they aren't in danger (although both Cybil and Angie disagree).

His last appearance is at the end of the game, where he wishes Angie and Derek well as they leave.

Under the Knife 2

Derek, Angie, and Adel meet Tyler shortly after they return from Africa, and he greets them warmly. He is eager to help treat PGS, and worries about the possibility of Amy showing symptoms. Adel is assigned to him as a mentee, and Tyler warns him that they'll be working hard. He claims that other students called him "The Demon," although according to Derek, Tyler made this up himself.

He is enthusiastic about Derek appearing on TV. However, Tyler is also shown to be a hard worker during this game, both at performing surgery and training Adel. He heavily encourages a relationship between Derek and Angie.

After Emilio's death, he is shown comforting Derek and telling him he made the right choice. He also speaks to Adel, filling him in on what happened when he contracted a disease and had to be operated on, though he doesn't explain that Derek has lost his Healing Touch.

Tyler is not seen again until after Derek operates on Kenneth Blackwell. He and Leslie Sears respond to the call, but only arrive once Derek has finished. Though he initially is about to wake Derek up, Angie stops him.

Later in the game, when Leslie is occupied assisting Stephen Clarks, Tyler needs to perform an emergency operation. With her and Derek's permission, he borrows Angie to help him, resulting in Derek later performing surgery alongside Heather Ross.

After the GUILT outbreak is stopped by the HOA, Tyler becomes visibly depressed at the idea of Caduceus losing funding.

He appears at the very end of the game, bursting in to give Derek a serum to treat the Neo-GUILT. He also helps dispose of the GUILT inside the tanks.


  • The age gap between Tyler and Amy can be estimated at about sixteen or seventeen years.