“For all the beauty and wonder of Buffy the Vampire Slayer though, branding itself into our culture and collective hearts, I have noticed one disturbing trend in the series: the emasculation of the male characters. I have a theory about this. My belief is that Buffy is, in fact, her own special breed of vampire. Whereas traditional vampires suck the blood from their victims, Buffy drains the testosterone from the characters she is involved with—this appears to be the true source of the Slayer’s power.”
-Sherrilyn Kenyon, “The Search For Spike’s Balls”
The book is here: Seven Seasons of Buffy