Joan Watson (born Joan Yun, Chinese name Yun Jingyi) is a consultant detective for the NYPD along with her partner Sherlock Holmes. She was originally Sherlock's sober companion, but when her contract ran out, they decided that Sherlock would take her on as an apprentice.
Joan is the daughter of Mary Watson, and sister of Oren. Her stepfather, had an affair, but her mother took him back. Her birth father fell out of the picture and her mother remarried Henry Watson. Joan was valedictorian of her class in medical school.
When Joan was a surgical resident, she became romantically involved with Liam Danow, whom she had met when he was her patient. When he later started using drugs, Joan hosted an intervention and drove him to rehab. Although he was better when he came out, he started using drugs again after. Later, when she was a surgeon and accidentally killed a patient, she was suspended for two months. As she couldn't trust herself anymore as a surgeon, she let her license expire. After her relationship with Liam, she had learned a lot about how to deal with drug addicts, so when she decided to leave medicine, she decided to become a sober companion. She takes Sherlock Holmes on as a patient after his father hires her.
When Joan meets Sherlock, he claims he needs no help to stay sober, as he tells her he is done with drugs. He suggests she should take the six weeks she's supposed to be his sober companion, and spend them as a holiday instead. After a fight, Joan says she'll request a new sober companion for him, but she later changes her mind and stays after Sherlock apologizes. According to Sherlock, she hates her job as a sober companion, but loves what he does. She denies this, but he claims that someone who needs two alarm clocks to wake up in the morning, is not enjoying her job. When Sherlock's father invites her and Sherlock out to dinner, Sherlock tells her that his father never shows up. She decides to go anyway, and at the restaurant she meets a man posing as Sherlock's father. Joan believes it is Mr. Holmes at first, but when he starts asking strange questions, she knows something is up. The man turns out to be Sherlock's friend named Alistair, a struggling actor, although he states Sherlock only hired him through his agent and that they've never met before. Joan later shows up at the bookstore Alistair works at, and asks him to tell her about Sherlock's past. She gets to know more about Sherlock's past with drugs, and about a woman named Irene. When she returns home, she asks Sherlock to tell her about the woman.When Joan's family visits, Sherlock defends Joan's decision to work as a sober companion to her mother who doesn't approve of her current occupation. Joan thinks her mother, Mary, doesn't like Joan's job because of selfish reasons, but Mary tells her that she thinks being a sober companion doesn't seem to make Joan happy, and notes that when they talked about Sherlock's work, Mary saw a spark in her, which she hasn't seen in a long time. When Joan's time with Sherlock is almost up, he offers to train her as a consulting detective. Joan refuses and says she has already taken on another patient. When a criminal from Sherlock's past brings up the memory of his past love, Joan decides to stay even though their time together is up, lying to Sherlock, telling him that his father had retained her services. When Sherlock's ex-drug dealer Rhys comes to him for help on finding his kidnapped daughter, Joan becomes worried that Sherlock will be tempted to start doing drugs again. Rhys offers to give Sherlock drugs, but Sherlock turns down the offer, and tells Rhys he never wants to see him again. Sherlock later reveals he has known that Joan stayed on as his sober companion even though his father told her not to. He tells her he is grateful that she stayed when he needed it, but claims that after some time, she stayed for herself as well, and proposes again that she should stay on as his apprentice. He tells her to take some time to think on it. She later accepts, and Sherlock starts teaching her.
Although she lived with her clients when she was a sober companion, she had her own apartment. She was evicted from her apartment when the man she had let stay there shot a pornographic film in it. When she later became Sherlock's apprentice, and partner, she decided to continue living at the brownstone until she could find an apartment.
|“||One way or the other, I'm going to be out of your life in a few weeks. Maybe you're dreading that day. Maybe you're counting the seconds. Either way, I'm going to make sure you're ready when the time comes. I promise.||”|
Every photo of Joan Watson on this wiki can be seen here.
|Jin May Wen||Yun||Henry Watson|
|Lin Wen||Oren Watson|
- First line: Hello? Yeah, I'm coming to get him in-- I'm sorry, did you say he escaped?
- Joan used to be a successful surgeon, but she abandoned her occupation when she lost a patient. 
- Joan turned a sober companion to continue to help people.
- Joan was hired by Sherlock's father to be his sober companion for six weeks.
- Joan's biological father is a schizophrenic homeless man, he and her mother divorced a year after she was born, the last time she saw him was over two years ago. 
- Joan occasionally volunteers at the local homeless shelter to help people and to find her father.
- Is a New York Mets fan.
- Owns an iPhone, and a Blackberry.
- Lived a few blocks away from Cobble Hill seven years ago when The Balloon Man took his first victim.
- Zadie Smith is one of her favorite authors.
- The fact that Joan's brother is named Oren is an inadvertent homage to Lucy Liu's character in Kill Bill, named O-Ren Ishii.
- Joan's portrayer, Lucy Liu, co-starred in Ally McBeal together with Robert Downey Jr, who, coincidentally portrayed the titular character in the live action film, Sherlock Holmes.
- On the show, Joan's mother is named Mary Watson. In the original Sherlock Holmes stories, John Watson's wife is named Mary Watson (née Morstan). Joan also has an ex-boyfriend named Ty Morstan.
- Joan had a one night stand with Sherlock's brother Mycroft back in London and once back in NY. 
- Joan revealed that she stopped practicing medicine in 2011.
- To some extent Joan knows Mandarin Chinese, we know this from Sherlock saying that he speaks Mandarin but not as well as he'd like, Joan responding that she knows it too, just not as well as her mother'd like.
Arthur Conan Doyle's Dr. Watson on Wikipedia, which Elementary's Joan Watson is based on.