Using his ability to control the chains, Kaayn really got free. But despite the terrible suffering, he did not hold a grudge against his friend, as he understood the reasons for his action. With difficulty, he reached a remote Revenant settlement, and his appearance (he still had no skin, he was exhausted and tormented by persistent pain. He interacted with the outside world only with the help of chains embedded in his body, like a giant grotesque spider, for his own body was shackled by pain and did not obey him) impressed them very much. Before that, there were legends about him among the Revenants, but no one knew before what really happened to him. Kaayn founded a small cult with their help, receiving the initiation name Kathean - "The Chainer". He did not manifest himself and lived in seclusion while his followers did all the work. At that time, in the Hem Valley (the name of the area where the events take place.), the institution of slavery was gaining momentum, and cultists no longer attacked peaceful people, conducting rituals with slaves specially bought for this (that is, by local standards, they acted within the law).

After a while, The Chainer completely recovered, and he got tired of playing God. He abandoned his followers, advising them to stop playing games, abolish the cult and live according to their conscience (as far as one can imagine a conscience in such creatures as Revenants). No one ever saw him again (or if they did, they didn't recognize him, because now he no longer looked different from the others, and he carefully hid his chains under his clothes). So, Kathean Kaayn was gone. But his followers did not listen to his words, and the cult stayed, gaining quite a lot of popularity in the future. And Aurelian, understanding everything and considering himself responsible for the emergence of the cult, did not ban it, and only issued several laws regulating its activities.

In real-time events, the cult has been around for thousands of years, and has undergone many changes. Kathean Kaayn is considered an invisible and intangible deity, who was named the God of Coercion. It is especially popular among some members of the Slavers Guild, who believe that by sacrificing to Kathean they attract good luck in their work. Worship of the cult is not very approved within even the Guild itself, which adheres to pragmatic views, but since this is not a violation of anything, no sanctions are imposed for it, the followers of the cult are simply looked at as cranks (there is a small parallel with modern Masons, however, in a much darker version). It is clear that no Kathean is already present in the cult, either visibly or invisibly. This is well known to the priests of the temple, who all possess the magic of the earth, which includes the ability to control metals, and significantly tear apart and drag away the bodies of slaves after a ritual slaughter. Such a show allows the cult to maintain popularity.

I also want to point out that the cult, yes, was founded by Revenants. But currently, most of his followers are humans and other human-like creatures. Revenants are generally small in number, so they would not be able to maintain a large cult. In addition, many of those who stood at its origins have long since left it. Revenants live indefinitely, so it's normal that many have gone through the process of rethinking their values and moved on their way.

As for Kaayn himself, he moved away from the capital of the revenants and settled in a dugout in the forest near a large village, and soon became seriously interested in alchemy, starting to create various mixtures with its help, and then learned how to create even living beings. Revenants, unlike classic vampires, are not afraid of sunlight. Therefore, he communicated with the locals without obstacles and gained a good reputation among them as a healer and a trader of useful potions. Having the appearance of a very young man from the very beginning, he does not arouse suspicion that a multi-thousand-year-old vampire is hiding behind his disguise (that is, everyone knows that he is a vampire, and one could guess, but the appearance confuses everyone). He lives quietly, thanks to alchemy he has found a way to extract energy from sources other than living intelligent beings, he no longer has anything to do with the cult.