In the clusters of fruits Yggdrasil lets loose special ones called Time Fruits float off as well. If a female, human or otherwise, were to encounter one of these Time Fruits they would bond to the female and make them an Immortal; said female would usually only become aware after suffering from what would normally be a fatal injury. However, if one of these fruits were to bond to a male they would become creatures called Angels, although there is nothing heavenly about them. These creatures are short-lived and violent, and are drawn to the female Immortals physically and sexually. Immortals suffer the same sexual attraction; whether they want to or not. However in the act of mating Angels will begin devouring the Immortals in an attempt to get at their Time Fruit. This is why Immortals attempt to kill Angels before they themselves are attacked.