Watson, as the normal narrator of the various accounts of his friend's endeavours, gives an accurate account of all characters that are presented to the reader, even if they lack the perspicacity that Sherlock Holmes is able to bring to the narrative. The introduction of Mary Morstan in Chapter Two of this novel is no exception. Note the following information the reader is presented about her character:
Her face had neither regularity of feature nor beauty of complexion, but her expression was sweet and amiable, and her large blue eyes were singularly spiritual and sympathetic. In an experience of women which extends over many nations and three separate continents, I have never looked upon a face which gave a clearer promise of a refined and sensitive nature. I could not but observe that as she took the seat which Sherlock Holmes placed for her, her lip trembled, her hand quivered, and she showed every sign of intense inward agitation.
Even though she is described as being "limited in means" through her rather plain and simple clothing, the admiration of Watson for her is clear through his identification of her as being unique amongst women and speaks of her "refined and sensitive nature." In addition, note the way that it is her vulnerability and fear that also seems to form part of the attraction that Watson instantly feels towards her. Mary Morstan is presented as a woman in need of men to help protect and guide her, and this is something that Watson seems to find appealing. The introduction to Mary Morstan therefore foreshadows the romantic attachment that will develop between them.