The Three Eyed Crow is the only character who would be satisfying as an overarching villain at this point in the series
*I want to preface this by saying that I think that the Three Eyed Crow is Brynden Rivers, the man Bran met in Dance. It would just be stupid to have someone else come out of the woodwork and say "Psych! Actually, I'M the Three Eyed Crow". Whether you agree with that or not, I'm going to be assuming that they're the same person for the entire post to avoid constantly repeating it
When I say main villain I mean actually either behind or a significant player in both the mystical side of things and the geopolitical side. Also, I guess by villain I really mean schemer, everything I say below could be true and Bloodraven could be the hero. But the series and his actions would still be morally grey enough to call him a villain, so I’ll leave the post as is. I would be OK with several other characters being extremely significant threats and causing mass devastation, and I would for sure be OK with there being no real villain scheming away behind the scenes and everyone just being swept up in a tragic combination of the forces of history and their own natures.
But for example, even though I have come around a lot on Euron after reading that WOW sample chapter a few years ago, I just couldn't deal with him actually having significant control over dark forces. It would be too much like when DC comics tries to have the Joker both dangerous because he's crazy and willing to do things everyone else is too sane to do and also the most meticulous schemer ever. Now, Euron as a crazy puppet who THINKS that he's in control until it's his turn to burn would be awesome. But on his own, not only does he not work for me, but he was introduced too late to be a satisfying main villain.
Really that's one of the biggest factors for me. Who was introduced early enough not to feel like a cheap copout? I think it comes down to Varys and the Three Eyed Crow, and only one of them makes a satisfying mystical threat.
Without any retconning or cheap handwaves, Bloodraven can be behind everything we've seen the Others do.
All tinfoil hats off, we know that he was behind the Three Eyed Crow dreams. We know Jojen was getting some dreams related to him that could easily be from him. It seems like he could have the same connection with Howland, and that could go back his whole life. It wouldn't be a stretch to have him be behind any prophetic dream that's influenced the characters.
Most of us think that he was behind a lot of the things Mormont's Raven says, and a lot of the suspicious things we've seen animals in general do.
He's in with the Children of the Forest, which gives the potential for him to be part of insanely long lasting plans stretching back even before he was born.
Most of us think that he contacted Euron as a child. I've mostly seen the theory that he's a failed apprentice bandied about, but when I thought about it I didn't feel like it made sense. We know Bloodraven has a stupid amount of power, especially for this setting, there's no way he wouldn't be able to kill Euron one way or another, and no way he wouldn't see what a big threat he was becoming. He's gotta be one of his tools. It's even in the name. Crow's Eye. George likes ironic stuff like that.
If you think that the Faceless Men are significant players, you can easily fit them in under him. If it's not satisfying for you to have Arya's Faceless Man currently in Oldtown ultimately serving Varys, then the Three Eyed Crow is really the only good option I can think of. The only way having someone transported across the continent chained in a cage for a mission makes sense is if you can predict the future and/or influence things through warging.
You can even fit him with the Red Priests, including Thoros and by extent Beric and Caitlyn if you really need to. At first I thought it would be cool if there was some sinister force or entity like R'hller in conflict with the Great Other, but at this point it's just too late in the story to be satisfying for me. It's gotta be a game of solitaire.
I recognize that this is almost entirely based on vibes and my own taste. I think that the most unambiguous foreshadowing for this is obviously when Melisandre sees Bloodraven and Bran in her fire and wonders if it's the Great Other. There's also the part at the end of one of Tyrion's chapters in Dance, when Moqoro says one of the most prominent things he sees is "A tall and twisted thing with one black eye and ten long arms sailing on a sea of blood". While this obviously fits Euron, it also would fit Bloodraven really well, and the very next chapter switches to Bran, who's apprenticing in the cave with Bloodraven. It reminds me of a similar cut in Dance, when Jorah has captured Tyrion and tells him that he'll deliver him "to the queen". That's the last line, and then we get a Dany chapter. Because of the way the chapters are named, the next word in the book is Daenerys. Obviously that's not something that the readers needed hinted at, but it's still a fun use of dramatic irony and casts Dany and Cersei as parallels. I think George could have been doing a similar thing with Moqoro’s line.
As for his motivations, there's only a few I could come up with:
Culling or eliminating humanity. This would actually make the Children of the Forest the greater scope villains and Bloodraven their tool. It would make sense for them to either want revenge or make a comeback and Bran's thought that men wouldn't quietly resign themselves to fading and being replaced by their conquerors would be dramatic irony and dark foreshadowing, which I think George does really well in this series
Countering the threat of Dany and her dragons. At first I kind of liked this idea, but honestly it seems really clear that something is driving Dany as well, and again I just think it's too late in the series for a R'hller like being to be revealed as behind half of the stuff that's happened so far.
Balancing mystical forces in some esoteric way. This could overlap with countering Dany and her dragons. I would be OK with it, but honestly I kind of hope we get something more concrete
Using a mass sacrifice to accomplish some mystical feat. This would overlap with all 3 other goals. I know people have theorized that Euron wants to become a god, maybe Bloodraven is using him to do that instead. Maybe the Children of the Forest are trying to somehow revitalize their race, not just eliminate their rival. Maybe the war between the Children and humanity caused shit to get out of whack and it needs to be fixed, otherwise even worse things will happen.
TLDR: I don't think that anyone but Bloodraven was introduced early enough in the books has been alive long enough, and has sufficient means and knowledge to serve as an overarching villain or schemer if the series is going to have one, which it doesn't have to
What do you guys think? Is there anyone else you would be satisfied with as a main villain/schemer? Would you even want the series to have one? And whether or not you think he can be called a villain, do you think that Bloodraven will end up having as much power, scope and foresight as I'm assigning to him?