While at the House of Night boarding school, fledglings are required to take lessons in vampyre history, sociology, and in the powers gifted to them as part of their transition into an adult vampyre. As a result, fledglings rarely leave the schools in which they live. The change from human to vampyre takes four years, during which the vampyre teenagers, known as 'fledglings', must attend one of the 'House of Night' boarding schools, and must remain in constant proximity to adult vampyres, as otherwise the fledgling will die. The marking of a fledgling, and the consequent gifts received as part of being a vampyre, are considered to be gifts from the goddess Nyx, the Greek personification of the night. Red fledglings appear to complete the change once they have made a choice to side with either good or evil, and their expanded tattoos are the same red.

Fledglings that die and then are later resurrected have their crescent tattoos turn red in place of the usual blue. Fledglings are 'marked' by a Tracker vampyre with a blue crescent-shaped tattoo on their foreheads when they become full-fledged adult vampyres, this mark becomes solid blue, and is eventually elaborated upon with the addition of further blue ' tattoos', which extend over their forehead and cheeks, typically taking designs related to some aspect of their personality. In the fictional world of House of Night, a small percentage of the world's teenagers are changed into vampyres when adolescent hormones trigger a strand of what is otherwise junk DNA.

This convention is also applied to the words 'vampyric' and 'vampyrism'. Instead of 'vampire', the authors use the variant spelling 'vampyre' throughout the series. Joseph Monastery, Tulsa, the basis for the Benedictine Abbey in the series The setting The Vampyre World

Untamed a house of night novel