Hey, everyone. I hope you guys had a happy holiday. Now that the Holidays are over, I'm looking forward to posting more of the thoughts I've been collecting over the past couple of weeks.
So I got done with the DLC and trying to piece together the timeline from a general sense.
1.
Byrgenwerth scholars discover the underground labyrinths and find evidence of Great Ones
2. Start exploring labyrinths and researching Great Ones and how to communicate/ascend/whatnot
3. The leaders of Byrgenwerth at a crucial juncture are Williem, Micolash, Laurence, Gherman
4. The discover somehow via rumors erc. That a fishing hamlet might have a lead on what they are researching
5. They go there and likely accidently murder the OoK either by pushing to aggressively or not realizing a viable fetus was still alive in the corpse
6. Probably killed all in the village to cover up their actions.
7. Now after this discovery is when the schism happens between Williem, Laurence, Micolash. All have their own views on how to proceed (eyes vs blood vs channeling/summoning)
8. Somewhere between 5 and 7 is when Rom ascended to Kin.
9. Laurence started the Church. Scourge comes out. Hunters founded. Lecture Hall research we see in DLC is occurring and overseen by Maria.
10. Maria is furious/grief-stricken when it all hits her regarding the lecture hall experiments and what happened in the fishing hamlet. I almost suspect she was not at the fishing hamlet when that went down and when she discovered the atrocities committed there in the past by Laurence and Gherman (with others but those two were the leaders she was apart of now) is when she threw her weapon down the well.
Killed herself too
11. Laurence knows what is going to happen to him and summons the Moon Presence to help. Turns out the MP is a bit of a trickster and instead of turning into a wolf he instead turns into the original Cleric Beast
12. Laurence is killed by the Hunter in the underground cell and the church buries their secrets even more
13. Gherman is heartbroken over Maria makes the Doll. Doesn't realize what a trickster the MP is and cuts a deal to bring Maria back to life. MP brings the doll to life and Gherman is the MP's bitch now
I left out a lot just trying to get a grasp on how the older lore went down
That's a pretty good take on the timeline. Interesting take on the motivations of the Moon Presence; most people interpret them as an outright benevolent or malevolent entity. It's possible that the Moon Presence, since they are so powerful and long-lived as a Great One, thinks the suffering of humans is amusing or interesting to watch. Kind of like
from Undertale, who grew bored with giving everyone their happy endings while stuck in a time loop and ended up dedicating himself to causing misery just to see what would happen. The MP could have grown bored with helping the people of Earth and eventually decided that all their gifts would be poisoned, just because the end result would be more entertaining.
Laurence transformed into a beast constantly in flames but lost his memory, so he wouldn't even know why he was being tortured. Gehrman would have his Workshop and Maria back, but in the end, what he got were only echoes of the real thing. I can see a trickster MP enjoying the tragedy of these results due to the pathos and irony.
As for why a trickster MP hunt Mergo... well, as a Great One themselves, they would know the baby Mergo would be a cause for great celebration. Maybe MP's misanthropy extended to their own race? Maybe they wanted to take away the hope in the future that Mergo gave the Great Ones out of bitterness or boredom.
Personally, I interpret the Moon Presence as being motivated in ending the Scourge of the Beast, no matter what the cost. Looking at the descriptions of the Chalices, particularly the Loran Chalices, insinuates that blood ministration and beast hunting are very old practices. The Pthumerians had their own version of the Scourge of the Beast, which arose from their use of the blood of Great Ones to heal their illnesses or grant them supernatural abilities. Since the Great Ones were so close to the Pthumerians and relied on them for companionship and reproduction, the Scourge of the Beast must have been terrifying for the Great Ones as well. Some beasts even gained the ability to emit electricity, which was deadly to Great Ones. It's likely the Great Ones viewed the beasts as negatively as the Pthumerians did and encouraged using talented warriors to hunt beasts down.
But in the end, the Great Ones left Earth and the Pthumerians behind. Since the Scourge was a illness that sprouted from the relationship between Great Ones and the people of Earth, it's possible they decided to cut themselves off from their followers for the safety of both races. Out of fear of the Scourge, the topic of close relationships between Great Ones and earthlings might have become taboo among their kind.
Killing Mergo seems to be the Moon Presence's ultimate goal. So it's possible that, while most Great Ones would be happy with the birth of a Blood Child, the Moon Presence sees Mergo as an abomination and a relic of their troubled past. (Perhaps MP's opinion of Mergo extends to Kin as well, which explains why they're on your hit list.) Since the Scourge of the Beast was reawakened by humans using Great One blood, the MP became active again to wipe out all traces of the intimate relationship the Great Ones shared with the people of Earth. With a more permanent break between races, both would be safe from the Scourge.
Now that begs the question why the MP would order for Rom's barrier to be lifted and for hunters to heal themselves with Healing Blood, since both actions result in more harm than good. But I think that, while allowing hunters to use blood vials would result in them turning into powerful beasts, it might have been worth the risk in the MP's opinion in order to train a warrior that could handle any foe. At first, their servant Gehrman tells you to "kill a few beasts, that's just what hunters do", as if Gehrman and the MP don't have much faith in new recruits. But as you kill more powerful beasts, you further prove yourself to the Moon Presence, so it uses Gehrman to eventually guide you to Rom and then tasks you with killing Mergo. By the end of your quest, the holy blood medium, the Child of Blood and many of the ascended humans/kin are dead, so many of the connections that humans have made to the Great Ones have been severed. Whether or not the MP gains the hunter as a competent new servant to replace Gehrman is up to you, but it looks like training you as a hunter turned out to be a great boon for the MP, no matter the negative effects.
As for breaking Rom's barrier, it does seem strange a deity charged with protecting both humans and Great Ones would order for the murder of a Great One, which results in misery and death for the citizens of Yharnam. But it's only after the Paleblood Moon rises that the player is able to fully uncover and undo the actions of the Institute of Mensis, who have been sheltering Mergo and beckoning other Great Ones to ill effect. The MP was willing to sacrifice the whole city in order to stop Mensis. Also, many of Yharnam's citizens were infected with the Scourge already, so the MP would likely consider trying to save the city a lost cause. Maybe the MP thought encouraging the city's implosion would further their goal of ending the Scourge of the Beast despite the loss of life. In that light, you could say the Moon Presence believed in fighting fire with fire and was willing to break a whole lot of eggs for their omelette.
I have a couple other interpretations of the Moon Presence's motivations and personality, but this is my main theory. The MP really is an ambiguous figure.
