When Helen Stoner arrives at 221B Baker Street to meet with Sherlock Holmes, he notes several things about her appearance. The first thing he sees is that she is shivering, and when he mentions it, she says it is from terror rather than cold. Holmes observes a return train ticket stub in the palm of her glove and correctly deduces that she has come to London by train. Moreover, noticing the mud spattered on her left sleeve, he correctly guesses that she traveled over rough roads in a dogcart as well; he counts the stains and points out that this would only happen if she were sitting to the left of the driver. Lastly, he correctly deduces that Helen's stepfather has mistreated her. He exposes bruises shaped like a handgrip on her wrist by pushing back the lace from her sleeve.

Helen is obviously scared.  She has been dominated by an almost archetypal "evil stepfather".  She has been put into a state of constant fear, inferiority, and relative poverty.  However, Holmes is able to see that she has courage, and that she is determined to beat her stepfather and regain her independence and her fortune.  She is more resilient than her situation would suggest, which is why Holmes agrees to accept the case.