Dr. Ewen first appeared as the mystery man that saved Elizabeth Webber from drowning, after she was thrown overboard by the deranged Lisa Niles during a boat party celebrating the publishing of Matt Hunter's research. Ewen rescued Elizabeth from the water, carried her to the shores of Wyndemere's Spoon Island, and then gave her CPR.
When she regained consciousness, he disappeared and she was later found and taken to the hospital by Damian Spinelli. While Ewen was seen onscreen saving Elizabeth and walking around the mysterious Wyndemere castle, his face was not shown to the audience, until December 13, 2011 when he formally met Elizabeth at Shadybrook Sanitarium.
Ewen had just gotten a job as a psychiatrist at Shadybrook and Elizabeth was assigned as his patient. Ewen and Elizabeth first met at Shadybrook while Ewen was painting and they began to bond over their common interest in art and painting. Not knowing that Ewen was a doctor, Elizabeth opened up to him and told him a bit about her life.
Elizabeth also had a feeling that she and Ewen had met before, not knowing that he was the man that saved her after she was tossed overboard by Lisa. On that day that Elizabeth left Shadybrook, she was blindsided by the fact that Ewen was actually a doctor and had been assigned to treat her. Dr. Ewen was later seen at General Hospital doing outpatient work.
Elizabeth later confronted Ewen on lying about who he was, but he quickly corrected her and told her that he never lied, she just made assumptions.
After Lucky Spencer, Elizabeth's long time love and the father of her children, left her, she went to see Ewen finally ready to accept his help and recognizing the fact that she needed help. Ewen then visited Elizabeth at her home on Christmas Eve and tried to help her deal with Lucky leaving. Once more, Elizabeth wasn't very receptive to his help, but before he left, he gave her some art supplies as a gift, which reinforced an earlier conversation they had about Elizabeth refocusing on her passion for painting.
On July 26, 2012, Ewen is revealed to have been the person holding Robin at Ferncliff for Jerry Jacks. When Robin attempts to escape and Anna is close to locating her daughter Ewen has her transported to a clinic in Switzerland. On August 13th Ewen kidnaps Josslyn Jacks from her bed and takes her to Wyndemere Castle where Jerry Jacks injects her with an unknown substance. He returns Josslyn to her house later that evening. When Josslyn and Alexis get sick he begins to question Jerry and about what is going on.
On August 23rd, Ewen goes to Elizabeth's home for a date. He kisses her several times and she stops him by saying she doesn’t want to rush things. She is trying to not jump into bed in relationships. He is frustrated but takes up her offer to sleep on the couch. The next morning, Jason comes in and sees Ewen shirtless. Jason says he was wrong about Ewen regarding his innocence. Ewen thanks Elizabeth for the night and leaves. After Ewen is gone, Jason tells Elizabeth he wasn’t wrong about Ewen.
After the water supply is contaminated Ewen hears about it on the TV while visiting Elizabeth. Patrick shows up to warn Elizabeth that Ewen has been working with Jerry. Ewen appears to leave to return to General Hospital, but actually stays and hits Patrick in the head, knocks him out and kidnaps Elizabeth. He takes her to a house and admits to working with Jerry. It is revealed that John Jacks stole the dead man's hand from Ewen's father and as a result Ewen's father died. Ewen followed the Jacks family to Alaska looking to get revenge for his father. When the cards were stolen from John Jacks, Ewen became his doctor.
Ewen eventually killed John Jacks by injecting his IV with a sedative. Jason arrives at the house and after Ewen shoots Jason in the leg and Elizabeth breaks free from his arms, Ewen tries to finish Elizabeth, but Jason shoots Ewen in the stomach. Elizabeth insits that they take Ewen to the hospital. At the hospital, Ewen tells Steve Webber to stop trying to save his life as he will die anyway and Steve is needed to help others. Ewen asks to see Patrick Drake. As he dies, Ewen attempts to tell Patrick the Robin is alive, but dies before saying so. His last word is "Robin".