Brador supposedly killed the first cleric turned beast and was driven mad by the experience
Does the game tell you he killed the
first Cleric Beast? I believe the description of his set only says he killed his friend who turned. This would be significant, because the first Cleric Beast is, in fact, Laurence, according to his skull. The Church probably then locked him up in order to conceal the horrors of the blood, and their experiments. They then gave him his own bell, which probably drove him insane, killing his old Church buddies.
The real mistery is the CONTRACT between Laurence/Gehrman and Moon Presence. What did it entail?
"The Third Umbilical Cord precipitated the
encounter with the pale moon, which beckoned the hunters
and conceived the hunter's dream"
is the latter part of the Umbilical Cord's description found in the workshop. Whoever this Umbilical Cord belong to was the final one needed to call on the Moon. Personally, I think it belonged to Maria, as it's found next to the Plain Doll...
It was most certainly Laurence who called on the Moon Presence. Laurence and Willem both wanted mankind to rapidly evolve, but had a disagreement on how to pursue it. Willem seemed to think filling his body with eyes would lead to this, possibly because Rom, a spider, had so many eyes.
Laurence was determined to try and make use of the Old Blood, but kept in his mind Willem's 'old adage' of "We are born of the blood, made men by the blood, undone by the blood. Our eyes are yet to open… Fear the old blood," in what is essentially the only CGI exposition in the entire game, which means it's prooooobably important.
In creating the Hunter's Dream, the Moon Presence essentially gifted immortlality to Gehrman and Bros (Ludwig was probably in on this too). After all, every time we die, we wake up right back in the Dream, able to continue our Hunt. Laurence however, had consumed the Old Blood and became a Cleric Beast and had to be put down, perhaps by Brador. Why was he in a persistent state of flame when every other beast in the game is terribly weak to it, though?
What did the Moon Presence want?
"It's said that all Great Ones lose a child and yearn for a surrogate"
If we consider the main definitions of surrogate mother...
1. A person who acts in the place of another person's biological mother.
2. An animal that is given another's offspring to raise.
...and you get the hidden ending and kill the Moon Presence, who's the one 'raising another's (MP's) offspring?' The Doll... Perhaps Gehrman's elite tinkering skills (as seen from his ability to turn every day clothes into Hunter's Garb, and being the originator of trick weapons) is what proved most useful in setting up this surrogate agreement in exchange for mankind's "evolution" (immortality in the dream). However, it was Gehrman's depression (mania) that led him to make it in the likeness of Maria. Perhaps the question as to whether he though of Maria as a daughter, or his infatuation was romantic is a red herring - what matters is the doll's
purpose, not her appearance.
This whole idea can be problematic if we consider one question,
"What caused Gehrman's mania?"
Was he always depressed by nature of being a mad genius? Was it because Maria said, "Fuck this shit" and booked after the Fishing Hamlet stuff?
What if it because he found out that maybe she was impregnated by the Moon Presence? This is unlikely as none of the others impregnated seemed to survive the pregnancy, buuuuut she is distantly related to Annalise who's also pretty much immortal.
Finally, what if his depression was caused by the fact he saw all his bros turn to Beasts? This might skew the timeline of events to the point where we have no fucking clue what's going on again.
Also of note: killing Gehrman and the Moon Presence in the hidden ending leaves the Hunter's Dream intact...