Comments posted to our Bloodborne Wiki
I took the time to piece together whatever amount of "lore" I could for this boss, mainly because most things I've seen are just mocking how easy it is to beat this boss.

It says in the Orphanage Key description (which the fight takes place in) that the Orphanage is where the Choir was thought up, and that it turned orphans into members of the Healing Church's "think tank," likely in the hopes of coming up with solutions to the scourge and blood evolution.

This may not be worth saying, but I would also like to point out that it was "shadowed" by the Healing Church, which in the context could be defined as:
1. "accompany (someone) in their daily activities at work in order to gain experience at or insight into a job"
2. "follow and observe (someone) closely and typically secretly"
Meaning that the Church presented the Orphanage by telling the yharnamites that it would simply by scholarships for orphans, though the work and experiences presented were in the interests of the Church alone, and possibly without the orphans being any the wiser.

It should be noted that the area is connected to the DLC research hall, and underneath the Living Failures boss fight. The Orphanage is also in the DLC as a garden tended to by variants of the bulging headed beings with the powers of the Church Orphans (I call the smaller emissaries that because I hate that their names are often the same as the boss, and to differentiate them), and some of the other patients mentions that they were there for doing something wrong, and the Living Failures certainly look like unstable crazed versions of the Celestial Emissary (their stronger powers but lack of Great One status could be that they did not maintain a stable state, which would be required for proper ascension to take place, hence them being called Living Failures). Even the patients that attack you without magic will utilize a version of the five hit combo of Church Orphans at times.

These patients are implied to be the way they were because of an eldritch parasitic bacteria in the water that they were to imbibe (which means to guzzle like alcohol or absorb through pores) that caused their brain fluid to congeal and move about like an organism, and that this was done in the belief that those who can gain a connection to the deep sea become connected to the Great Ones in some way.
An interesting description for a brain fluid reads "Once, a young girl had an older brother who was determined to become a doctor, and so she wilfully became his patient. In the end, this led to their encounter with the Eldritch Truth, for which they considered themselves blessed." It is my personal belief that these children were members of the Orphanage, and had the idea of imbibing eldritch water in the first place, which appears to have allowed them to realize the Eldritch Truth and popularized the idea of gaining the "eyes on the inside" by doing this.
So perhaps these patients were Orphanage members being transformed into the "potent unseen thinkers" by forcing them to gain the "eyes" necessary for transcended, and therefore advanced thought, making them capable of perceiving the voices of Great Ones. Adeline may have been an example of the final success (though since this technically occurs in the past, with which you interfere with there, it likely was not her who did this originally) in which a patient transcribes the voice of a celestial attendant (key word Celestial) and discovered the ability to become true Kin by transforming into Lumenwood.
This plant is clearly connected to the Celestial Emissary and the Church Orphans, as they grow from the flowers tended to by the patients of the past (and the area is known as the Lumenflower Gardens), and the Living Failures grow from the plants in the Lumenwood Garden above the Celestial Emissary boss garden.
When you equip the Milkweed rune, you become a Lumenwood Kin. And this is kind of a stretch, but it could be said that the structure of the tree is reminiscent of the Church Orphans' head build, and they share the same colors as well.
I also want to mention the fact that one of the brain fluids points out that mankind has potential, but it is rarely noticed and realized, until after the fact. This hints that the Church Orphans are the result of messy, forced evolution of mankind that Laurence wanted, which to be honest seems worse in comparison to Wilhelm's method that is utilized in one of the game endings.
It has been predicted that mankind will eventually evolve a large headed appearance similar to aliens, and that alien encounters are simply encounters with evolved humanoid races, which is technically what you experience with this boss fight. So perhaps the Lumenwood Kin eventually move beyond their tree forms, and become the organisms that the Church Orphans are, with one of them possibly becoming a Great One and possessing ascended manipulative powers over the cosmos.
Lastly I want to mention Iosefka, who is part of the Choir, creating Church Orphans out of people. If visited after defeating Rom, she will be suffering from a writhing in her head, which she attributes to the ascension into a higher being. She was likely trying to replicate the successful ascension of the Celestial Emissary by using the water and brain fluid method, meaning that it does indeed work, and she even developed a umbilical cord native only to Great Ones and their mates (though the cord may have been put there by Oedon, since before Rom dies she can drop the Oedon Writhe rune, which can either refer to the writhing brain fluid or be a mistranslation of the word wreathe as in making a wreath. Then again it is heavily implied that Oedon's child was with Arianna, as mentioned in her cord that her corrupted blood made her susceptible to this liaison, in reference to a sexual relationship that is done secretly and unfaithfully)

So to summarize my idea for the lore of this boss, I have theorized that the Celestial Emissary is the first and only human being (probably an orphan) to ascend to Great One status using the methods advocated by both Laurence and his Church, and that the Church Orphans are the ones that became Kin but did not become Great Ones. As a human that became a Great One, this Celestial Emissary is named this because there is now a solid connection between man and Great One that shows that humans can ascend, and honors Laurence's will by succeeding where he did not.

If any of that seems unbearably stupid, please comment your own theories, and I may change my belief. This was to both encourage a discussion of lore for this boss, and simply to give my impressions, so I would very much enjoy seeing other people's lore ideas.
Nice theory. Although believe the celestial emissary is not a true great one, but is more of a messenger created to communicate with Ebrietas.
This is definitely a good, if not great, theory. However the woman in the clinic after rom is not iosefka but an imposter doctor who is part of the choir. She turned the actual iosefka in to one of the mobs that is by the door and cainhurst summons at the clinic. This is shown as the mob drops a iosefka blood vial which was given to you by the actual iosefka before being turned in to a mob.
However, the Emissary's trophy specifically states that it is a Great One.
I thought they were just the result of the old experiments in the research hall involving the imbibing of water. Water and ice, as well as mold and the color blue, are all associated with each other and with the cosmos in the world of Bloodborne. The growth of their heads is likely based on hydrocephalus, or the enlargement of an infant's head due to high levels of water in their brain, and their proximity to Ebrietas calls to mind the condition known as "water intoxication," in which a person experiences severe hallucinations due to drinking too much water and inflating the cells within their nervous system. I was also intrigued by the statues surrounding their arena, considering they look so similar to the Moon Presence, furthering the theory that the Moon Presence is using Hunters to harvest the blood of the Great Ones in order to give itself form.
The easiest boss fight ever in the game.
Nah, Hemwick Witches were easiest for sure.
Kind of like the Deacons of the Deep in Dark Souls 3.
Best way to kill the Celestial Emissary:

1: Go into the swarm and quickly identify the boss; he'll be the one without a health bar over his head.
2: Kite the swarm away, and rush him. Use a Shaman Bone Blade on him.
3: Dodge away, and let the swarm attack him.
4: To make it more brutal, be behind him and use any weapon with an R2 thrust.
Tried this, didn't work. It wore off after he transformed and he killed me. Waste of Shaman Bone Blades.


Joined: Wed Jan 17, 2018 1:29 pm
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Go behind...then thrust...

I died twice to this guy. Should I should just let Gehrman kill me at the end.
I didn't realize until recently that it has the ability to buff all of its allies. I usually kill it too soon for it to happen, but I was goofing around and it suddenly raised its hands to its face as if it was praying, then raised them over its head, and a massive blue corona spread throughout the arena, granting all of the surviving mob severely boosted offense and defense. The eyes of the affected allies started to glow more brightly, almost like an enemy that has stolen your blood echoes, except the color was different. I think its health has to be at 25% for this to happen, and I'm pretty sure the buff lasts as long as the affected enemies remain alive, and any replacements that spawn later will go back to being pathetically easy to kill.

Maybe it isn't new knowledge, but I don't think I see it mentioned anywhere on this page? The boss actually almost killed me that time, lol.
I'll be honest i always struggle with this boss compared to fhe others i just get swarmed and stuck +alot of their magic actually oneshots me. Maybe my health os too low or something but i alwayd get 1-2hit killed by progectiles and swarmed and stunned
You should try the shaman bone. It's hilarious.
Using a charged attack with the 2H hunter axe cuts the little guys down like a lawnmower. Solid fun.
The difference of difficulty between this boss and the one following after it is ridiculous lmao it gives us a hope thinking that we are actually good
Threaded Cane makes this a cakewalk, no different from clearing trash.
Even easier if you have somehow ran through the DLC and got the beast cutter, which is just the Hunters axe combines with the threaded cane
Ayy lmao?
I don't get it, would someone explain this?
I thought I'd be able to find the explanation beyond "lol memes", but that is all I've been able to find.