Saint Yeryca is an Etrandish Titanist saint, also legendary pagan priestess-turned-goddess. Her legend has given birth to man other deratives. She is a legendary figure, her existence - or the existence of any of her alleged descendants - was never proven. In the Titanist religion, she is the patron saint of mothers and young girls. In Human Paganism, she was a goddess of barriers, defender of the mortal realm from demonic forces.
There are some people who claim to be Yeryca's descendants, but none of their claims are taken seriously.
The pagan Yeryca/Gæryca
The current Etrandish name Yeryca (Etrandish: Yeryca ; IPA: [jɛɾʏkʰɐ]) originates from the Old Etrandish Gæryca (Old Etrandish: Garwca ; IPA: [ʝærykɑ]), which in turn originates from the Proto-Human Garjuka (Proto-Human: GARJWKA ; IPA: [ɣɑrjukɑ]). It is said that Yeryca/Gæryca was a pagan priestess, who was blessed by the gods in many ways: not only she had a talent for magic, she also didn't need to learn spells, as their usage came naturally to her. The divines also blessed her with beauty that makes even the best-bred princess green of envy, smarts that put wise men to shame, and a voice that soothes even the most enraged. However, there was one thing the gods didn't grant her: eternal life.
In fact, she was given the opposite. Her duty was to protect the boundaries between the mortal realm and the realm of the demons, Nortiimus, but the power to do that was not something she could teach to anyone - it was inherited, therefore, she had to get married and bear a child who inherits her powers. To make it worse, once her daughter was born, she began losing her powers. As her daughter became stronger and more mature, Yeryca became weaker and weaker, even though she looked as young as ever. When her daughter reached the age of 16, Yeryca fell ill and died. The same happened to Yeryca's daughter: she got married at the age of 18, had a single daughter, died when her daughter turned 16, and the circle would continue on.
It is said that Yeryca herself did not die like her descendants - she ascended to godhood, becoming the protector of the mortal realm from demonic influence, and the patron deity her female descendants.
The titanist Saint Yeryca
After the Kingdom of Etrand was founded, there was a debate whether the legend of Yeryca should be considered truth and Yeryca be made into a titanist saint/angel - like several pagan gods - or be considered little more than silly pagan superstition. In the end, the earlier won, and now in the Church of Titanius, Saint Yeryca is considered a human who turned into an angel when she supposedly died, and now serves as a patron saint to mothers and young girls.
Possible origins of the legend
Some believe that the legend of Yeryca comes from the Kingdom of Steelhelm, where there once was a queen, a beautiful queen, who ruled on her own for a while during the 9th century BEKE. Then, bowing to pressure from the tribal leaders, she got married and bore a daughter. She simply couldn't get pregnant after that. After her daughter turned 14 or 15, the queen unexplainably fell ill, started seeing troubling visions and lived for two more years only. She died in a mysterious disease when her daugter was 16-17. The same would happen to her daughter, the exact same.
Many believe that the legend of Yeryca was inspired by these two queens of Steelhelm.
Possible relationship to the Bryantid snake-eyedness
Some believe that a descendant of Yeryca was different from all of her predecessors by giving birth to twins - a boy and a girl - instead of a single daughter like all of her ancestors, and that the boy was the ancestor of the the Bryantid dynasty, and it would be from that boy that the Bryantid Kings of Etrand would inherit their genetical disease that causes them to starts seeing visions and develop some sort of dementation at an advanced age.
The royal family has denied any connection to or possibility of descent from Saint Yeryca.
During the early 6th century AEKE, a woman named Sifléda Sirrám Theudilt, magician by profession, made a claim that she was a descendant of Yeryca, claiming that using magic came naturally to her, and she saw things that others did not. The Church, rather than arresting her for blasphemy, did not take her claim seriously and dismissed it. Sifléda gave birth to a son, not producing any more children. The previously always healthy and youthful woman inexplicably became bedridden when her son turned 17, and soon died. Her son however produced multiple children from two wives, and died of old age.
At the end of the same century, a nobleman named Marius Londbert - great-great-grandfather of Ladislaus Londbert - made a similar claim. Being the first male in history to ever claim being descended from Yeryca, people just laughed him off. The snake-eyed nobleman claimed that his eyes changed colour after his son was born, and that he started seeing strange visions regarding a certain gate between two worlds.
Marius Londbert wasn't the last man to make such a claim. In the mid-8th century, several men in their early-to-mid thirties claimed that they were struck by a strange disease after their sons and daughters were born - while their wives who were actually giving birth remained completely healthy -, a condition they - according to their claims - inherited from their forefathers. None of these were taken seriously.
The last female to claim descent from Yeryca was Ymierra Émasirick in the late 8th century, who claimed that both of her parents died prematurely soon after she turned sixteen, and that she - just like both of her parents - has natural talent for magic. She claimed "This can't be a coincidence". Ymierra is still alive, but said to have barely survived a grave sickness when she was thirty-four - coincidentally, when her daughter was sixteen. Her daughter gave birth to a son doesn't seem to share the condition of his mother and grandmother.