Jonah Carver was The Pacifier, a vigilante who worked to clean up the streets of Salem. He'd capture criminals and tie them up or beat them up, leaving a pacifier around their necks. Lexie ran into him during one of the incidents, and she ended up helping him for a while. He was kicked out of medical school for his crime, but was later allowed to return to school. Lexie was kicked off the police force, but then decided to go to medical school.