HOSTILITY

  
Putting aside the obvious effects that result from direct stimulation of erotic body parts, it is hostility – the desire, overt or hidden, to harm another person – that generates and enhances sexual excitement. The absence of hostility leads to sexual indifference and boredom. The hostility of eroticism is an attempt, repeated over and over, to undo childhood traumas and frustrations that threatened the development of one’s masculinity and femininity.

-- Robert Stoller, Sexual Excitement