So the immediate:
Henry doesn't seem completely out of his mind. In fact, he seems to perceive better than in the past that his wife isn't necessarily on his side. I welcome that recognition. He remains impassive as to his/her fate, which means he may not do anything to resolve this. He's in his happy place, with God. Margaret is cast off and away. But still looking for that string to tug at which could make her into a factor again.
The work as a whole:
Wow, this is an awesome ask. But I have the benefit of having read it all in a go, pretty much. Otherwise I might find some areas fuzzy (I'm sure I still do -- hard to keep it all in mind at once).
First I would say this work has been a pleasure to read not just because it's an awesome story told by a remarkably talented author. It's also a pleasure because it's a far fuller fleshing out of the Wars of the Roses for me than I've ever had before. I had been vaguely aware of the events as a "civil war of sorts in English history" and my history classes I'm sure taught some details that I'd forgotten, but I've not read any books on it. I really appreciated that you would tell, as you went, the real history and the alternate history in tandem as they occurred. This is the beauty of well-done alternate history -- creating plausible alternative paths and explaining how certain changed events also changed consequences and realities.
I would say yes, the characters -- those that matter -- are fully realized and well written. They're believable in their actions, the dialogue is believable and carefully crafted. You're doing what I tried to do in Fire Warms, which is to adapt what we know of a historical figure's thinking and personality into a character who can live and breathe outside the limitations of "known" history.
Cecily was confident and assured and had firm direction at the beginning. As bids for power failed, or almost succeeded and then faded, and especially as she lost her home, and eventually Edward, I sense that her spirit has faded some. Now that she's Queen, she will take the perks that come with it, but I sense the fire in her belly is less. Or maybe that's just because she hasn't had need to drive Richard so much, because his fire seems to have increased.
Richard and Henry were both frustratingly tentative in the beginning. Richard didn't even know what he wanted, or couldn't admit it to himself. But as he faced those same failures of bids for power, or near-success and then rejection, it eventually hardened resolve in him. I've always sympathized with Richard (and Cecily) from the very beginning, and it was hard to at times because he often made the wrong choices.
Now that he's King, Richard has lost the reserve that marked his early days. Maybe the loss of his son proved to him that it's not a game at which he can play. It's almost as if the spirit and determination that Edward eventually developed was transferred to Richard. Maybe Edward in his youth had the vision that his father knew but refused to see, and once Edward was gone he no longer had the luxury of not seeing what he didn't want to see. Now that Richard is King he's single-minded, and I see that he so wants Normandy back. And he seems to have a vision of how to do it, even if not everyone sees it the same. Will it become his Moby Dick and destroy him? I hope not. At present I judge that he is both able and determined, and will see it through. Not without some challenges, and I'm sure Margaret lurks in the background to provide them. I also wonder how Warwick will help and/or obstruct Richard's vision -- the relationship which was always strained has now become fraught.
Edmund is a good and able spare. He seemed to have Richard's caution and reflection in his personality while Edward took to the other side of the father's personality. You have developed him some, but in a way he's always been your spare, and I think his development remains mostly in the future, and has only just begun "at the now". I sense that he will rise to the occasion and be successful when the time comes. I suppose Edmund is "your creature" to a large degree since his early death OTL means there wasn't a whole lot known about him.
Edward negotiated his own transition. He really didn't want reality to intrude upon his dreamily imagined "present" when he was young. He didn't share his father's drive, and seemed mostly to want to ignore all the kerfluffle (hints of Henry?) and live his life the way he wanted it. As Somerset became drawn away from him and Warwick became a mentor, Edward became an apt pupil and learned the fire and passion and determination of Warwick, and in some ways eclipsed him (in your story at least). So Edward was often tugging his father along behind, "Dad, come see this, come do this! Why won't you come?" When he came into his own as a military and political leader, he was the man who his father should have been. And so one wonders whether they could really both exist at the same time as partners. More on that later...
Warwick was the reckless guy driving Richard's policy and vision far faster than anyone wanted him to. Which was an awesome element to see! I quite enjoyed the consternation he caused. He's always been a valuable (I didn't say valued) member of Richard's team, and I feel for him deeply -- I feel his resentment -- as Richard continues to ignore and put off Warwick's advice and withholds rewards which (in my opinion) Warwick clearly earned. Warwick should be a duke by now -- or so I think and so HE thinks. But others who did little and less are advanced and rewarded instead of him. Gosh that has to burn!
I'm not going to speak on Henry, as a hundred (two hundred?) comments from your readers have voiced my thoughts on him. He's utterly frustrating, and it's even more frustrating that it's largely not his fault. He has the personality he came with, which wasn't one suited to rule, and so others have led, pulled, manipulated, deceived, and ignored him and his wishes. Henry's driving passion was always to see England at peace, which is a noble goal. But he blindly refused to see how he could make that happen, and instead invited conflict into his midst in so many ways. Believable? So far as I can tell you're representing him as he was historically, and plausibly creating reasons why he acted as he did. It's no less a tragedy, and it's no less believable because we cannot fathom how he could have been so passive.
Margaret of Anjou is someone we all hate, and who we refuse to have sympathy for. As you've said, she's made her bed (and invited many to it!). But she's far more comprehensible because she is a creature who we see often in history. She knows what she wants, She knows what trappings she needs (or wants) to demonstrate her power. She seems out of her element now that she's lost those trappings. She's... .... I'm thinking back to my own Louis Napoleon here (Fire Warms) -- the guy who was a political genius but a military idiot and refused to believe he wasn't great at both. Margaret thinks she's really good at politics, but in reality she's only really good at scheming, manipulating and getting revenge -- at creating an atmosphere of fear where people do what she wants because they're afraid not to. But she doesn't miss the need to sometimes use a velvet hand to manipulate. So long as she lives, whether she has the power and leverage she wants, she is a danger simply because she's so vicious and driven.
I've done my tribute to Buckingham already, in a past post, and I don't know that I can improve upon it. Another character who I greatly miss is Salisbury. He was frustrating in his own way -- always counseling caution when Richard was already doubting and inclined toward inaction. But he was a genuinely good man (in your telling). I sense a sincerity and loyalty in him that Richard always needed, and it's sad he's no longer with us.
Exeter is fun and I'm enjoying your telling. You say you've taken him outside his historical role, and I'm enjoying that. I do actually sympathize with him, even though he's often working against what I want to see for England. Like Black William, he's unpredictable, and can show up unexpectedly in a starring role. I do question how angry Richard can still be with him despite his saving his life. But this may come around again and we may understand better as the story continues.
One last comment -- Allen Leighson. Gosh he's developed alot since his early days with that rebellion (the name is on the tip of my tongue but I can't remember). He was the English "shopkeeper" of cultural history, but he turned into an advisor to the future king's children, and saves Edmund's life. Got to love the development and look forward to what he'll do as the story continues!
To the key transition:
Edward, in some ways, was quickly becoming the kingly figure his father should have been. And really -- both historically and literarily -- there wasn't really room for two people in the same role. With Edward in the picture there wasn't room for Richard to grow into his role as King. And so it seemed clever and entirely logical to me how you manipulated the "alternative" to the history. Edward, I have to tell you, was starting to annoy me -- the cocky, know-it-all kid who tells the adults what they need to do and who pulls off the heroics everyone expects of the adults. I'm not talking full Wesley Crusher here, but he was too big for his britches in my personal opinion, and needed to be knocked down (or knocked off!). I know that historically this conflict was resolved by killing Richard and allowing Edward to take on the role he really wanted anyway. But I like your solution of knocking off Edward instead and allowing Richard and Edmund to continue. Blank slates from here on out, which is a joy for a writer who has hit his stride in writing for them! (this reminds me, btw, of Fire Warms' Kaiser Friedrich III, whose reign I turned into much more than it was historically).
And Somerset -- this jarring departure from real history w/re to Edward MUST create a wholly different result than the historical result did. I'm curious how that all plays. I didn't give Somerset his due in the character outline above. In some ways he's been his father's son, and doesn't have much of a will of his own (it seems to me). In other ways I feel like he has more drive and sense about him, and COULD turn into a key character as the story continues. I have no idea what happened historically, so I depend on you and your fans to instruct me.
I'm sure I could keep writing, but this seems like quite enough to digest (it's already 2/3 of the size of your updates!). In short -- great work!
Rensslaer