|Occupation:||Founder of Oswald Asylum, Doctor, Psychologist|
|Relationships:|| Clara and Mia (Patients)
Fran Bow (Patient)
Grace Dagenhart (Aid)
Dr. Marcel Deern (Colleague)
León Castillo (Colleague)
For his in-person appearance, Dr. Oswald appears as a man in his late 80's. His hair, including his beard, mustache, and eyebrows, has turned white with age. He wears a redish brown coat with a pale blueish-green undershirt and pants, as well as a pair of brown slip-on shoes.
In the old photo of him alongside several other characters (see the image gallery on this page), his hair is visibly darker, likely brown or black in color. He wears a white lab coat and undershirt along with dark pants and shoes.
In either appearance, he is seen using a wheelchair.
Not much is known about Dr. Oswald Harrison's personality, but he seems to be very into his work. He will do anything to complete his tasks, even murder. He has partnered with Grace, Fran's aunt, to continue his studies on Fran and those who can see the other realities. From his actions, it can be inferred that Dr. Oswald is very ambitious and driven, if not a bit mentally unstable himself. His motivations in the game seem to be directed towards gaining knowledge as opposed to fame or fortune, as he never mentions his discoveries pertaining to twins to have given him a great deal of recognition yet doesn't seem to mind. However, we can also assume he is vain to an extent as he displays pictures of himself throughout the asylum in addition to naming it after himself. He also could be considered very cold or even cruel as he has no qualms with murdering people to get what he wants, including children and his own patients and employees (as we can see he had Dr. Deern constrained to a shock therapy chair and would perhaps have had some unsavory plans for him had Fran not intervened). He is very manipulative as seen through several points in the game: him getting Fran's nurse to claim that she was deceased, despite the nurse knowing that was not the case, getting Fran's drugs switched to a higher dosage or perhaps dangerous version of Duotine, manipulating Grace into betraying her sister and niece, and recruiting Remor, the prince of darkness, to be his mere lackey and to do his dirty work. His charm is not infallible, however, as Dr. Deern, Lucia Dagenhart and Fran seem to see right through Dr. Oswald's charm and ambition.
- Dr. Deern reveals that Oswald experimented on the twins Clara and Mia and is the one who sewed them together to see how their DNA would react.
- He worked with Lucia and Grace Dagenhart (Fran's mother and aunt) when they were younger.
- There are three self-portraits of him throughout Oswald Asylum: one in the main entrance, one in the dining room, and one in the basement.
- He carries a gun very reminiscent of the one found in the nurse's desk at the beginning of the game. While this could be considered a coincidence, it could also imply a deeper relationship between the two which is further reinforced by their history of working close together (a photo found of the team studying twins shows her as well as Dr. Oswald among others), and her willingness to lie to protect his and the asylum's integrity.
- It is revealed in a photo that he at some point knew León Castillo, and that both of them worked with Grace & Lucia Dagenhart as well as Mia & Clara Buhalmet.
- Judging by a picture of him in his youth, it can be speculated that he was either born with leg weakness or was in some sort of disabling accident as even when he was young he required the aid of a wheelchair.
- The character of Dr. Oswald Harrison may be inspired by Dr. Josef Mengele, a German Schutzstaffel officer and physician in Auschwitz concentration camp during World War II. He too performed grotesque human experiments and particularly enjoyed experimenting on twins.