The Hunters and the HeirOne of the Caryll runes, Heir, says: “Perhaps the 'Heir' is a hunter who bears the echoing will of those that went before him.” We've already touched on the idea of the Great Ones requiring a surrogate but what exactly does that mean? We know that every Great One loses its child and yearns for a surrogate, which implies that though these beings can impregnate humans the resulting child never survives long. This can be seen lategame when the prostitute Arianna gives birth, an event precipitated by the encroaching red moon, and the 'child' is briefly alive.
This was the goal of the School of Mensis, a splinter of the Healing Church. Mensis may have been an individual, but the name also refers to the group as a collective, and they sought communion with Mergo, Queen Yharnam's child. This was achieved and they entered a nightmare – though the experience resulted in the “stillbirth of their brains.” In the Unseen Village the Mensis acolytes' withered corpses can be seen positioned at various points, with every one turned towards the moon.
The School of Mensis had its own hunters, who kidnapped citizens for sacrifice, and in the Unseen Village these victims can be seen petrified as they tried to escape the ritual – men, women, children all.
Incidentally, the presence of the bell maidens here emphasises the importance of 'echoing' as a theme and explains the reasoning behind multiplayer. The original bells were discovered in the labyrinth and their chimes echo across worlds, allowing hunters to cross dimensions, albeit briefly, and aid each other in different dreams.