By the time she adopted the moniker DD39s Kristina Melba online, she’d layered herself like a confection: a childhood nickname, a number from a long-forgotten username, and Melba for the toast her grandmother used to make when Kristina finally tried something brave. People who met her on performance nights called her Kristi Top; friends called her K. To strangers she was a flash of costume and a voice that could hold a room.