@Legioner8  
Thanks a bunch.

@Raido_
 
Here’s the video where author theories about the reproductive cycle of the Great Ones. Link
 
And here’s a similar theory that goes even more in depth about it. Link

@Legioner8
 
We are aware of the SEVERE necropost, but if perchance you are still active, we are interested in that link.

@CobaltTheMadMage  
That’s what I said.  
I recently heard an interesting theory that everything that happened in Bloodborne is a part of The Grate Ones reproductive cycle orchestrated by Oedon.  
Oedon is a sound and flow of Blood, everything that uses blood is Oedon’s inadvertently follower. All most important NPCs that help you in your hunt (that guy in the chapel, Gascoigne’s daughter, the Blood Saint you save, even Imposter Iosefka before killing Rom) drop Oedon runes if you kill them. And the Doll is there to make you stronger through the usage of the essence of Oedon, the Echoes.  
I would’ve given you the link, but that whole thing is in Russian  
The theory itself never explain why is there the manifestation of Oedon in the Hunter’s Dream, that is probably belongs to the Moon Presence. But I have my own theory on that one.  
So the Moon Presence is Oedon’s child and Gehrman is now Moony’s surrogate. He is there to feed it. When a Hunter submits his life all those Echoes should go somewhere right? So all Echoes that we accumulate during the Hunt Doll is processing into something that makes us stronger and after our death are used to make Oedon’s child stronger. That’s why Moony is trying to adopt us if we kill Gehrman, it needs its wet nurse. And if we kill it as well…  
Well, it’s only better for Oedon, we absorb all the power and become an Infant Great One filled with Oedon’s essence, become even more powerful than our predecessors, giving Oedon even more powerful offspring.  
Well, something like that.

@Legioner8  
Perhaps Oedon, given her ability to manipulate Blood Echoes?

@CobaltTheMadMage  
Yes, but she is still there after we kill the Moon Presence, so I really doubt that.

@Legioner8  
Either Oedon or the Moon Presence, considering the latter is the one in charge of the Hunter’s Dream itself.

@Dragonman461  
Well she has a Pale Blood so it is safe to assume that she is on of the Great Ones, and her ability to manipulate the Echoes suggest that she is somehow connected with Oedon (maybe its manifestation)

I always felt like the doll played a far bigger role than we could really see, and I just wanted to hug her so badly.