Because Sebastian and Claude wouldn't stop fighting over Ciel Phantomhive, both Alois Trancy and Ciel Phantomhive dropped their contracts with their demon butlers. Demons cannot return to Hell without a soul so the two butlers were forced to find another soul to form a contract with.

You worked as a night nanny for overwhelmed mothers with newborns. You were walking home from work at around 5:30AM when you could feel a presence following you. It was dark and you were alone. Suddenly, a man with jet-black hair and red eyes plopped in front of you, a creepy smile on his face. Then another man with gold eyes plopped behind you, he had an emotionless expression on his face.