The Immortal Beloved

Not as much a coven, secret society, or cabal, as they are a support group.

They have a syndrome, yet unnamed. They refer to themselves as Immortals, although that's not completely accurate. They can be killed as easily as anyone else, but they are far more resistant to the effects of time, poison, and disease.

Symptoms:
- Always female.
- Race seems indeterminate. They have been born to and recorded among all races and ethnicities, but their indeterminate appearance means they are often accused of being bastards or children of infidelity/rape/etc. 
Some have described them as looking like a crossbreed of all races... or Brazilian. Quite a few have turned up hiding in places where the genetic mix of the population makes any breeding a crapshoot.
Footnote: a very few of the most recent ones have been subjected to genetic fingerprints, but each case confirmed that their fathers are indeed their fathers, and genetic markers show nothing out of the ordinary.
- They don't smell completely right. While their bodily odors are fairly normal, most of them have a subtle attractive component to their personal scent. Described variably as "Sweet", "Enticing", or "Sexy", many attempt to conceal it beneath "a strykynge parfumee" [sic], though this doesn't always work. 
- Very intelligent, as children are often far more advanced than their calendar age. Many could be considered geniuses.
- Unnatural/supernatural/supernormal abilities often manifest with the Immortal Syndrome. The most common are Psychic abilities, most often clairvoyance/"TrueSight", or clairaudience/Psychic Hearing. They usually try to downplay this as being a part of their high intelligence, being "extremely perceptive" and having Insight rather than Truesight. Partly due to this, "Spin doctoring" skill is quite common.
- Health is always excellent, showing incredible disease and infection resistance. Wounds and injuries will heal perfectly, with no scarring, given enough time... and they have plenty of that.
- Always sterile. A few may exhibit maturity characteristics, i.e. menstruation, growth of breasts, etc., but most do not.
- They grow and age very slowly, extreme cases appearing to be less than a quarter of their calendar age. This seems proportional - e.g. at 60, appearing to be 30-ish. 
- Very long lived. Most confirmed cases lived for over 150 years, though disbelievers may speculate that they're younger, just resembling an older relative.
Believers claim that the Immortals are older than they're playing on, and trying to hide their history. Other Immortals know better.
- To escape notice, nearly all have learned to assume new identities as time goes on. The best ones will have a string of birth and death certificates, or old family bibles that back their story up. Family trees that don't branch and look more like vines are a common sign of this, though most have been creative enough to dodge that. Rising literacy rates have made this harder to do in the last few centuries.

Lore among the Immortals has many personal tales of wandering and ostracism, assuming new identities as they travel. Life on the run is a common trope. 
One legend tells of a woman who left every time a chieftain died - she'd "gone missing" who knows how many times.

A few had been found when they were arrested for identity theft.

For one example, the oldest proven Immortal was 194 years old, with records of all her assumed identities: oldest birth record was 1706. First assumed a new identity in 1735, when she claimed her birth date was 1716. She assumed a new identity roughly every 20 years, though during the 1860s she went through six identities in five years - that war was quite a mess. Disappeared around 1900, was known to be in Galveston around that time, presumed dead from the disaster. 
A journal from another Immortal confirmed that she had at least three more identities planned, with documents to back them up as needed. "That could have easily gotten her through 1945."

Only a few hundred of them exist world wide, and only recently have they been able to reliably find each other. Genealogy websites have helped them unearth hiding immortals, looking (as above) for family trees that have no branches and long straight stretches that seem to have no relations.

Roughly once per century, there is one Immortal who is truly extraordinary, taking all of these factors to the extreme...


"Pleased to meet you. My name, for now, is Melissa Larson."

Born September 1977; as of 2020 still looks like a grade schooler. Still doesn't have her wisdom teeth yet. 

Had to get notarized statements from her parents, the bureau of vital statistics, several doctors, and a midwife who attended her birth before she could take her driving test. When she took said test age 18, she could comfortably pass for a 7-year-old. 
She routinely got stopped by incredulous officers, and several judges had to reprimand said officers for demanding that she be punished.