This is part of The Secret History of ST-OM
This is a case of a particular entity. Unlike most others, this particular type is not sentient. It is the non-corporeal, energy based equivalent to a cat. It feeds on the emotional energy of a specific person. This entity will bond with an unsuspecting human and live as a neural symbiont. Until its host dies. Then the Symbiont will "fix" him, returning the host to life and creating a further bond. Afterward the host will not age. The host will be cured of most serious injuries.
When its host is beheaded or chopped into tiny bits or blown to smithereens, the unfortunate entity must quickly find a new host. It has minutes to live without one.
If the only option is an already inhabited host body, then the two entities will engage in their own life-and-death struggle. This usually makes for a huge light show, and makes the surviving host as high as a kite, feeling invulnerable and empowered.
This is actually one entity eating the other.
The reproduction cycle of this entity, as well as its life cycle is not known. Victims of inhabitation by these entities are notoriously reluctant to allow examination.
Many of the Immortals have suffered persecution and outright torture at the hands of people convinced that they were supernatural evil. Not a few have been burned at the stake and successfully killed. In the 1970s Ben Richards was pursued across the planet by an obsessive billionaire, intent of vivisecting Richards to learn his secret.
Due to this hostile reaction it's not long before most "Oldtimers" learn to conceal their identities and natures. Oldtimers are almost natural undercover agents. Almost uniformly, Oldtimers resent being pressed into service by spy agencies and security services. They frequently disappear when contacted. This tradition continues until the current day 2376.
Before the truth of the condition of Immortality was known, A complicated mythology was built up around the condition. A mix of rules of engagement, and a great game, and a guide to etiquette among the Immortals. Older Immortals handed down this lore to newer ones. Swords and Sword combat remain favored weapons among immortals who conflict.
Earth throughout history. Presumeably other planets have such people as well - In the Secret History of Jay Trek
- Connor McLeod
- Duncan McLeod
- Flint -- Oldest known Oldtimer, born c.2000 BCE. Off planet and doesn't play games.
- Richie Ryan
- Nick Wolfe
- Carsen Bardo -- Described as a brute of a man. A firm believer in the immortal myths.
- Carlos Geureva -- Killed Carsen Bardo on a lonely road, and paid the price.
- Christopher "Kit" Walker -- "The Phantom", the Ghost that walks. He does not like Pirates.
- Barnabus Collins -- Bought in heavily with the Vampire myths.
- Darla Aurelius
- Liam "Angel" Collins
- Drusilla Landau
- William "Spike" Marsters
- Nicholas de Brabant
- Lucien LaCroix
- Janette du Charme
- Ben Richards
- Dana Scully -- 20th Century. Demonstrated oldtimer traits, missing since the 21st century.
- Jerry LaSaille -- Not a typical oldtimer. Born 1948 CE.
- Allen Strand -- AKA "Brother Mark" AKA "Athelstan" AKA "Grandpa". Born c.1100 CE. He is believed to be the second oldest of the Oldtimers.
- Janos Scozeny
- Catherine Rawlins
- Richard Malcom
- Stephanie Anderson -- Current Commander of the USS Savensu T'ness NCC-101734
- Georges Le Saint Devereau
In Play This condition of immortality directly replaces Vampirism, from Urban Fantasy Magic.
The fact that Allen Strand and that Stephanie Anderson are Oldtimers because of this "energy being symbiosis" is established in Epiphany Trek