Vitality

Vitality is a measure of the strength of a person's soul; it plays a large role in the "life" of ghosts and projectors in Orpheus. Vitality has a number of vital functions in Orpheus; it is used to power Horrors, allow a ghost to materialize in the living world, determine how many connections a spirit or Hue has to the living world, and how fulfilled a character feels in a spiritual state of existence.
When a ghost becomes a ghost, the process is extremely traumatic. A soul is essentially ripped from the body when a spirit is created and much Vitality is lost in the process. Some ghosts with particularly strong wills manage to regain this Vitality once they have settled themselves, but most spirits cannot. Those who lost much of their connection to the living world when they lost their Vitality become hollow shells of their living selves and are essentially unable to function other than repeating a few simple actions or recalling one or two memories. This process is what creates a spirit who is classified as a drone or a blip.
In addition, the more Vitality a spirit has, the more independent they are and the more capable they are of feeling positive emotions. Those who only have the capability to accumulate a few Vitality cannot be truly happy. The most independent spirits, the ones who can accumulate large amounts of Vitality, are also the ones who are capable of feeling great euphoric emotion. It is for this reason high-functioning hues, in spite of their independence, tend to be more morose than high-functioning spirits; their consumption of pigment in life limited their capability for gaining Vitality in death.
There are many ways to recover Vitality; resting is the most common. However, Vitality can also be shared between members of a Crucible, gained through Willpower, or even by negative methods such as tapping into their Spite or stealing it from another spirit. However, as Vitality is a positive energy, the most desired way to accumulate it is through positive actions. One of the best ways to accumulate Vitality among Orpheus personnel is to help a spirit "move on", also called Salvation or Transcendence.