LOS ANGELES -- When veteran TV producer Greg Berlanti was invited to adapt the novel “You" about a seductive charmer with a murderous streak, he immediately fixed on former “Supernatural” producer Sera Gamble as his collaborator.It may sound “horrible” but was the opposite, Berlanti explains.The book by Caroline Kepnes had "all the great things I love about Sera's writing. It's pulpy and addictive, but also highly intelligent and smart, and has something to say about our culture, our society,'" he said.“You,” starring Penn Badgley as the violent and disturbed Joe, became a worldwide hit for Netflix after a low-key U.S.