What does Holmes learn about Helen by observing her?

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.