Insertion is the procedure by which a soul is implanted into the body of a new host. It is considered to be a very simple procedure which "any soul on the street could perform in an emergency". Typically, insertions result in a loss of the host's sentience, with an anomaly being humans with knowledge of what is coming. As a rule, insertions are only performed by Healers, the soul equivalent of a medical professional. But it is still unknown where the actual insertion is medical equipment came from.