The success of The Magicians trilogy stems in part from its self-awareness. Lev Grossman wields his familiarity with fantasy genre fiction to critique and alter the usual formula. So why do his female characters all serve the same purpose?
…he’d almost certainly be familiar with the infamous tradition of “Women in Refrigerators,” coined by comic fan Gail Simone in 1999: It means, basically, that female characters are often killed off or otherwise grotesquely traumatized (raped, tortured, paralyzed, stripped of superpowers, etc.) to motivate angst on the part of male leads.