In Sir Arthur Conan Doyle's "A Study in Scarlet," the first Sherlock Holmes novel, the meeting of Sherlock Holmes and Dr. John H. Watson is described. The novel begins with Dr. Watson returning to London after serving as an army doctor in the Second Anglo-Afghan War. He is looking for affordable lodgings in the city and is introduced to an acquaintance named Stamford, who happens to work at St. Bartholomew's Hospital.
Stamford, aware of Watson's need for lodgings, mentions that he knows of someone who is also looking for a roommate. He suggests that Watson meet Sherlock Holmes, a peculiar and brilliant man who has a room available at 221B Baker Street. Stamford believes that Holmes, being an eccentric character, might be a good match for Watson's need for interesting company.
Curious to meet this potential roommate, Watson agrees to the introduction, and Stamford takes him to Baker Street, where he introduces Watson to Sherlock Holmes. The two men quickly strike up a conversation, and Watson is both intrigued and impressed by Holmes' keen observation and deduction skills. Despite finding Holmes a bit eccentric, Watson decides that he can tolerate the detective's quirks and agrees to become his roommate.
Thus, the meeting arranged by Stamford leads to the beginning of a close and enduring friendship between Sherlock Holmes and Dr. John H. Watson. Watson's role as Holmes' roommate and chronicler of their adventures becomes a central aspect of the Sherlock Holmes stories and contributes to the success and popularity of the series.