Dr. Rosa Ballard

Doctor Rosa Ballard is a doctor (presumably head doctor) at Delphi House and former colleague and apprentice of Peter Mason.

Background
Dr. Ballard is a doctor that started to work at Delphi house house some time after Peter Mason and Lucien Flowers founded the mental hospital. She is shown to be a caring figure with a passionate sense of duty. She was very close to both Alodie Carter and Peter Mason. She mentions one time she was about to get fired by Peter but Alodie stepped in and prevented it. Besides having medical knowledge, she also seems to have a degree in psychology(or at least she’s acquaintance with the matter) based on her knowledge and use of the Therapy invented by Peter which helps people recall traumatic experiences of forget events of the past(this later is highlighted by Kirstie Caulker in one of her conversations with Erica) Ballard seems to be also a skilled perfume maker.

Present day
At some point in time she became the head doctor in the facility. Being the one who orders around nurses and care helpers. She also developed a serum that has the ability to control people; By using the petals of Oleander, the target would experience hallucinations which aver very close to reality. This serum, combined with the therapy, are even capable of modify people's thoughts by making them forget about events in their lives.

Delphi House
Dr. Ballard and David Caulker meet Erica Mason and Duncan Blake for the first time when they both arrive to Delphi House. Dr. Ballard is the one who introduces Caulker and herself to them. She shortly after takes Erica upstairs. She also mentions knowing Erica's parents and remembering them quite fondly.
 * If Erica roams around Delphi House when they first arrive, she would peek on Dr. Ballard and Caulker discussing some matters.

Day 1
Shortly after Hannah has an episode Dr. Ballard shows up. Depending on what Erica did is how Dr. Ballard would address the situation.
 * If Erica Manages to calm Kirstie down Dr. Ballard would show up after Kirstie went out looking for her. She would reproach on Tobi's behavior for mocking Kirstie and would inform Erica Sargent Blake is looking for her.
 * If Erica Fails to calm Kirstie down however, she would hear the screams of Kirstie and rush into the room. She would then see Tobi trying to grab a gold of Kirstie and would the care helpers to seize Tobi. She then would attempt to calm Tobi with a sedative. Depending on what Erica says shortly after is whether Dr. Ballard injects Tobi or not.

Sometime after the discussion held by Erica Blake and Flowers. Dr. Ballard would assist Erica in a therapy that helps recall traumatic events experienced by people if Erica decided to cooperate. She would question Erica after the therapy is over about the sketch Erica drew while under the therapy.
 * If Erica chose not to cooperate, Dr. Ballard would ask Flowers to show Alodie's death certificate to Erica.

At lunch time, Dr. Ballard talks to both Erica and Hannah about the power Oleander flower had in ancient Greece and how priestess would use it to see visions of the future.
 * If Erica comes across the Delphic Epsilon medallion. Where she has a flashback of the dismembered hand holding the same medallion. Dr. Ballard attempts to calm her down, explaining that the whole staff received one each.

If Erica did not help Hannah to make perfume. Dr. Ballard would ask either Hanna or Lucien to give a diffuser to Erica.

Day 2
Dr. Ballard is first seen on day 2 when she rushes to assist Hannah having another episode after seeing the piece of human skin that was in the present addressed to Erica.

Later at night, after the murder of chief inspector Caulker, Dr. Ballard comforts Kirstie over the death of her father. She then meets briefly with Blake where Blake questions Ballard's true intentions with Erica.

Erica sees later at night Dr. Ballard performing the same therapy she performed on Erica. This time however, she is injecting some sort of serum into Tobi's bloodstream.

Ballard's fate
Depending on what Erica does at the end, Ballard's story changes. Dr. Ballard could either survive or die at the end of the game.

Erica breaks into Ballard experimental room where she is having experiments on Tobi. She aims her gun to Ballard and commands Ballard to wake Tobi up. Dr. Ballard does her best attempt to manipulate and convince Erica that she shouldn't be here and that she is just helping Tobi. Erica could choose to Shoot Dr.Ballard mid way through the conversation or Spare her. If Kirstie shows up, Ballard would run away before Erica could react.

Notes/Trivia

 * It is believed that despite of Sparing Ballard, she would die in the fire if Erica decides to Burn down the Delphi House.
 * This is not explicitly stated. However, at the end of the game it says Erica's enemies burned down if she burned down the place.
 * Dr. Ballard apparently is also the one who is behind Hannah's murder as well as Tobi's friend, since both were 'healthy' before they started see Oleander petals in their dreams.