Rosamund Mary "Rosie" Watson is the daughter of Doctor John Watson and the late Mary Watson, the goddaughter of Sherlock Holmes, Molly Hooper and Mrs. Hudson. She is now raised by a single father after the death of her mother in "The Sixth Thatchers". Sherlock also seems to help raising Rosamund by the end of the third episode.
She was named after her own mother's birth name.
Series 3 Edit
Mary and John consummate before marriage, resulting in Mary being pregnant. Sherlock reads the "signs of three", realizing that Mary is pregnant after her nervousness. He also states in his speech he will always protect the three of them, including John and Mary's unborn baby.
Later Rosie's parents learn that Mary and John are expecting a baby girl.
Series 4 Edit
Rosie is born in "The Six Thatchers" and later baptized with Mrs. Hudson, Molly Hooper and Sherlock Holmes as her godparents. After her mother is killed while protecting Sherlock, Rosie is left with her godmother Molly as John grieves for Mary's death. Later, her father is shot by Eurus Holmes Rosie's godfather's sister.
Sherlock: "John has a daughter. He may wish to say goodbye."
Mycroft: "I’m sorry, Doctor Watson. Any movement will set off the grenade."
-Sherlock and Mycroft
When Eurus creates a bomb, she has it land on the carpet when Sherlock, John and Mycroft are talking together. When Sherlock says that if they die, John should at least say goodbye to his daughter, but Mycroft says that any movement, the bomb will go off and Mycroft apologizes John cannot say goodbye to her.Rosie appears at the end of the episode where she is first held by her godfather before she is handed over to her father. They later go out when Lestrade comes for John and Sherlock's help with another case.
- John wanted to name the baby, but let Mary name the baby after making up with her at Sherlock's parents' house.
- Her name was going to be Catherine, but her mother went against the name
- Sherlock later attempted to have his goddaughter named after him in "His Last Vow", before learning she was a girl. However, he insists she would be called Sherlock again, Mary and John tell him its not a girl's name.