As a teenager, Felicity Hopkins discovered that she was able to sing her charges to sleep instantly and then get them to perform tasks for her without question. Realizing her talents could be more profitable to her, Felicity set her sights on real estate tycoon, Harold Cross and his wife Sabena. While working for Mr. Cross, she found her talents worked on adults too, and that is when Felicity made her move. She ordered Harold to divorce Sabena and marry her instead, but a mindless husband became awful for her when it was really only his money Felicity was after. She ordered Harold to leap to his death from their penthouse apartment, but Sleepwalker
was there to save him. Still a mystery to his new home, Sleepwalker was considered a threat, but Felicity offered him a chance to be seen in a positive light – with her help. What she really wanted was to use the alien for her own purposes, so she called the phone of Sleepwalker’s human host (unknown to her) and sang him a lullaby. Rick Sheridan fell under Felicity’s thrall, and Sleepwalker had no choice but to obey. She even sang a rhyme for Sleepwalker to make sure she had him under her spell, and together, the two committed robberies all around Manhattan. The papers had dubbed her Lullaby, and she announced Sleepwalker as her bodyguard. However, once Rick was out of harm’s way, Sleepwalker turned on his "master" saying that her powers could never affect him because Sleepwalkers never sleep. Lullaby was turned over to the authorities along with the stolen merchandise, and it can be assumed that Lullaby is still paying for her crimes in jail.