The Healers' Language

Surviving oral tradition makes it clear that the Healers were always at least a bit secretive. However, before the persecution of the Church, this was more of a precaution than a day-to-day necessity. These families had learned the hard way that they were some of the first put to the sword in Roman conquest, since conquerers of all stripes realized how easily their groups could turn insurgent. 

The Healer's Tongue

The most significant unifying force among these healers was their language. Thousands of years old, it began as a combination of common ancient languages, with their own words invented here and there. It had no official name, but its speakers passed on and graffitied a single word from it wherever they could, to show their fellow healers they weren't alone. The word was thiedra, one of their many words for humanity's collective life force. The more religious of their youth attributed it to their gods, especially the Egyptian goddess Isis, affectionately nicknamed Isis R'thiedra, or Isis as Humanity's Soul.

Book Burnings

Many, including healers, would assume that this language was a shield against the coming Plague's persecution. Of course, the ability to communicate in secret saved some, but depending on ethnicity or gender, it was sometimes a detriment. Suspicion of independent women or immigrants runs deep, and while their fellow healers were simply viewed as sorcerers hoarding immunity powers, bigotry was a lightning rod. These were the kind of people burned, not for being witches who could weather the plague, but because they were blamed for its emergence.

The senior members of their community saw the pain and corpses of their kin, and though they feared they were overreacting, they gathered their children and made the hardest decision of their lives. What information they could memorize, they did, but what they could not was lost. They set entire libraries aflame, fearing more death. Since so many healers blamed for the plague were caught at their studies, it was the only thing they could think of to do. The risk was steep, and entire histories were lost, but it was a low price for millions of human lives.

When questioned, the elders responded with their line of logic. They were all terrified of losing vital healing information, but if they all died, said information would be indecipherable anyways. With a few exceptions, they burned every last text they could find. Until the late 1920s, they thought they had lost everything, but the abilities of Life's Cavalry should not be underestimated.

An Alternate History of Plague Doctors

No one remembers the Black Death better than healers. Both metaphorically and literally, these cats that caught the plague rats were put to the sword and forced to go underground. They memorized and burned their literature, and they say the bonfire was so large it could be seen from France to the Vatican. Mothers taught daughters under the guise of "religious studies", and when the priests came knocking, they held out biblical commentary on how this plague was a punishment from the Lord.

Many, many times they thought of emerging from the shadows, but between the witch burnings and rampant colonialism that followed the Middle Ages, there were few safe places for these families. Most of them worked as physicians or nannies, hoping that their jobs would give them some cover for their more... subtle forms of magic. After all, they still wanted to heal. It was, often literally, in their blood.

However, all these years of hiding had taught them that plain sight was the best place for their operations. When they were working stiffs, people noticed how their families never got sick, and when they would visit plague-ridden children, they woke the next day miraculously better. Perhaps it was an unwillingness to question what little working medicine they had, but the townspeople forgave those of them who did this in doctor's garb. After all, your appointment with one of these mysterious healers was better than any plague doctor.

That realization washed over them slowly as the 20th century began. From the Bibles they carried with them to the medical societies that denounced them as quacks, they had always adorned themselves in what hated them. Then the "Roaring 20s" came.

The children of these healers found themselves taking things a step further, and when they went to parties surrounded by their own, they danced in plague doctor masks. Hundreds of black robes whistled under electric light, and the whole room smelled like sweat and potpourri. They had truly gone all in, and surprisingly, their parents applauded it. Besides, the war against death had a new enemy by the name of polio, and they needed all the help they could get.

Now came their time of light. They began to transcribe their histories, first in scraps on secret notebooks, then heading towards the libraries they still waxed poetic about. Where the pre-medieval healers had groups, they formed societies that stretched across the world.

The most famous of these societies, known as Life's Cavalry, led the charge. Its members were young and ambitious, and they recognized that their abilities were a double-edged sword. So, it comes as no surprise that when it came to picking a uniform, they chose the garb of plague doctors.