It was unknown whether it was a Deity or a Devil involved in its creation, but when a devoted believer of the God of Humanity lost his/her life, a mysterious power was used to concentrate all the blessings they received into their brain.
As the blessings of the God of Humanity were related to memories, knowledge, and experience, it was something a human could naturally possess. And hence, once other Deities came to know of it, they began to investigate.
One such result was the 'Lingering Attachment.'
One of the uses of Lingering Attachment was in the creation of familiars. Some Deities used these brains to create familiars to guard their territory. And since the source of these Lingering Attachments was their own believers, they could achieve it.
Every faith had its fair share of fanatical believers. So, such things had been happening for decades now.
