Let's speculate about the Plot!

• Gebel has no real plan as of the game's events outside of being a generic doomsday villain. Sane Gebel probably just wanted to make a safe haven for him and Miriam.
  
• Going off of that, hosts to the curse are ostracized, discriminated, and actively sought out by lynch mobs as they are seen as bad omens. (well they aren't wrong)
• Miriam is going to fall completely under the curse's influence a la Gebel only to escape it through plot bs willpower/friendship. (I hope I'm wrong on this one because it's been done to death.)
• If we are going for sequel hooks either Miriam or Gebel is gonna get dragged to hell. (my money's on Gebel, I bet 100 Zimbabwe dollars)
• Gebel curbstomped the alchemists guild during Miriam's curse ritual making it so that it was only a part of heart that was crystallized; this is also why she went into a coma and Gebel didn't.
• If the above isn't true and Gebel wiped the alchemists guild after the ritual then the sheer shock and difficulty of the ritual caused Miriam's coma.
• Going off of the above Gebel destroyed the guild for Miriam 
• Crystallizing the heart is much, much harder than crystallizing the skin. As a result Miriam, the last person to undergo this ritual, is the only one with a part-crystal heart
• Zangetsu hunted demons before Miriam's coma but moved to England with his fellow redshirts demon hunters because of the greater demand for demon hunters there. In short: economics.

Gebel turns out to be gay and is just going through an emo phase with too much power on his hands once Miriam smacks the crap out of him for awhile with a Fashion Today magazine and then sends him to Scottsdale as punishment

I always saw the game having a main enemy that is actually satan. I'll still miss the dracula angle because he's such a cool gothic figure but I really do feel the game needs a main villain that is bound by some nature of reality. ( in the sense that it's something not completely made up within the games story)

Hmm...a fine set of questions indeed.

Ritual
-I don't really think they were supposed to be sacrifices. I'd say they were supposed to be more like "remote controls." I don't really see why a demon would have to take orders from a human unless that human has power over them.

-Another question would be why the alchemist would try to summon demons anyways. Personally, I think they did it to "reestablish" themselves. Considering the time period Bloodstained takes place it, a lose in faith in magic wouldn't be surprising. Well, if you can control an army of demons...you can do pretty much whatever you want.

-Why did there even have to be a ritual in the first place? From what I can tell, Gebel was able to summon a horde of them without much problem.

Magi-Crystal Curse
-Miriam may have been picked because she was "ripe" and "disposable." Considering the fact she was in a coma-like state for 10 years we can assume that they really couldn't have used a person that was too old. A child would be a tender age if they were chosen. Now, let's also remember the fact that Miriam is an orphan so nobody would really notice her disappearance if they were to fail and accidentally kill her. (Now I made myself sad)

-Since we've yet to see what a "full-body" curse looks like, I would assume that is the secret. Gebel might transform into this in the game considering how close the curse is to engulfing his entire body.

-Also, have you noticed that the marks on Gebel's body are much darker and red than the ones on Miriam's? The same effect can be seen in the picture of Miriam when the curse starts to spread. It may just be for effect though.

Miriam
-I feel like she was just convenient to use.  She was but a child when they picked her up.

Johannes
-I think he's pretty suspicious to be honest. He'll probably fit more an "advisior" role most likely.

Gebel
-Given the way he reacted, I highly doubt he participated willing. However, he could have volunteered and wanted to back out when he learned of what could become of him. His feelings and the alchemist themselves probably accelerated the curse so it took over rather quickly.

-I don't think Gebel even knows what he is doing now. He had good intentions at first but...those were quickly lost in the echo. 

-I think he'll be a final villain in one of the endings. If he is the real threat or not, I have no idea.

Zangetsu
-I would be surprised if he was a boss or mini-boss. I can only guess parts of his personality through what little I know. However, he definitely doesn't strike me was the forgiving type, especially since he lost his arm, eye, and a lot of his friends. My vote is that he'll just attack Miriam and Johannes because they are alchemist who brought the demons there in the first place. 


Overall, I feel like most of the story will be unraveled via cut-scenes and in-game items. The enemies, themselves, would probably give an insight of what truly happened. I mean, the "Morte" looks like it could have been another living creature before it became what it is.