Sherlock Holmes is the ever-observant, world-renowned detective of 221b Baker Street. For all his assumed genius and intuition he is virtually omniscient in these stories, and Holmes becomes more accessible in the context of his constant posturing and pretension.
Holmes lets down his guard and admits of a fragile ego. When challenged at the beginning of the book—Mortimer calls him the second best crime solver in Europe and Holmes lets down his guard and asks who could possibly be the first. By and large, however, Holmes' ego is kept in check by a constant dose of adulation from Watson. Holmes regularly announces some absurd and unsubstantiated conclusion only to mock Watson by revealing the most obvious of clues. In the end, Holmes toys with his associates (and particularly Watson) at least as much as he flouts his enemies, equivocating, misleading, and making fools out of them only to up his own crime-solving cachet.