Jeannine was Jeff's little sister who was born before he killed his parents. She was born with a disease that made her eyes purple and pink.. She was sent to an orphanage and adopted by her new parents. They kept Jeff a secret until she was 10, when she read about him. She was super angry that her parents would hide that from her, so she decided to become like Jeff by bleaching her skin and cutting her mouth. She then killed her parents with a knife and used their blood to dye her shirt with the words "I <3 Jeff" in honor of Jeff. She then went on a long journey to find her long lost big brother, killing anyone who got in the way. Soon, she found him, and she told him who she was. Jeff didn't recognize her at first, but then he saw her eyes and remembered because he had seen her when she was first born and recognized her strange purple and pink eyes. He told her that he would take care of her and would allow her to join him on his killings. She was super happy about this, and she went along every day to help him kill his victims.
Yes, she is 10, and yes, she can kill adults. SO WHAT! She's related to Jeff, so she's a strong as him of course! IT MAKES TOTAL SENSE!!! >:(