aaaaaaaaaa oh my thread explosion… I’ll try to respond to as much as I can, but apologies if I don’t hit all of everyone’s points… It doesn’t mean I don’t appreciate all of them!
First off, I was already working on a few more little tweaks to part 1, and I just uploaded them. They are VERY small – not worth replaying the whole game for. After hearing some good thoughts from @Ponku, I tweaked the text you get if Guen touches Lancelot but still wants to be faithful to Arthur. If she has sex with Arthur before the second day of the battle, she can choose an option like “I don’t care what that was with Lancelot; Arthur’s more important” instead of just thinking that she’ll never respond to Arthur like she does to Lancelot. A Guen who kisses Lancelot but says at the end that she just wants to manipulate him will now get a bit of text commenting on the physical reaction to touching him. And then, just now, thanks to @Ramidel’s great suggestions, I added a more aggressive line telling Lancelot to get out of the dressing pavilion, and a “no point putting this off” lead-in to the first opportunity for sex with Arthur. @Marjade is right that the old version wasn’t meant to imply that Guen was enjoying herself too much if she wasn’t, but I think the new lead-in choice adds some good variation. Many thanks, @Ramidel! 
@Gadriel and @thesunfloweramazon I am really struggling with how to enable a cohesive asexual and/or aromantic path. I’m determined to make it work to the best of my ability, but it’s tricky with a pseudo-historical world where sexual identity terms seem jarringly anachronistic. (I replaced the term “lesbian” with “of the Sapphic persuasion” for that reason.) I tried to create a dialogue option where Guen could explain to Morgana that she’s asexual, without actually using the term asexual, and it turned into a ginormous mess that was way more than the game could support – in real life that can be a big, complicated conversation, and I don’t want to trivialize it. (Same thing happened when I tried to make it so Guen could tell Arthur she’s a lesbian… his inability to understand how two women could have sex was rather fun to write, but then it all got way too complicated.) So I’m going to try to keep things mostly unlabeled, and just have paths in which Guen can simply not have sex, or not want sex, and/or romance. As the game develops, I’d love to hear any thoughts you might have on that.
@thesunfloweramazon I will NEVER mind loads of text! Thank you for all of your thoughts. I think a lot of people have read Arthur as charmingly sweet and innocent and puppyish, and he is all of those things, but he’s also an extraordinarily privileged seventeen-year-old who’s so caught up in his own savior-complex that he can’t see how hypocritical he is. He wants to bring an end to violence, but he loves thinking and talking about battles (unless he loses). As you say, he thinks he’s going to end the monarchy, but it never once occurs to him that he might not get married and have an heir. It would never occur to him in a million years that Guen might not ever want to have sex with him… and if Lancelot hadn’t warned him that she might need some time, he would have been way beyond confused if she didn’t immediately jump into his arms the first second they were alone. Because who wouldn’t want to help him save the world by being the most wonderfulest babymaking queen ever? Of course, Arthur isn’t stupid, and he genuinely wants to be a good person. Given time and perspective, he could change.
Part of the reason Arthur can’t think outside of a blood heir is that that’s exactly how he came to be king. His Pendragon blood is literally the only reason Arthur was accepted as king by anyone – in this version, it’s what enabled him to pull the sword from the stone (more on that in later books). But yes, if a blood heir doesn’t appear (or, at least, a blood heir he feels he can acknowledge), he’ll have entertain some alternative ideas.
Which brings me to Mordred… 
First off, I should say that no, there are no vampires in this game – sorry. (There are vampires in my New Arcana novels, though. *cough*shamelessplug*cough*) @ricepatrick182, the dreams are just super-short sequences you get if Guen doesn’t talk to anyone at night. @Dolphinzgirl I was being cagey about it for awhile, but somehow I ended up admitting that yes, there will be a possible Mordred romance, though it won’t be as long-term as the others since he’ll only be an adult in the last two books.
As in the dreams, Mordred (as an adult) will be cocky and full of himself but not Joffrey-level sadistic. Neutral Evil indeed. He’ll have too much power for his own good. If all goes according to plan (a big if), there will be a clear reason why he has the magic powers he does, and even why his eyes are that color. @OtherGrimm It would be unlike me not to take advantage of the potential irony in Guen having slept with either or both of Mordred’s parents, not to mention a few other similar circumstances that may arise. In any case, Mordred will indeed resent Arthur (@MaraJade), feel that he is the rightful heir, and most likely call Arthur out on some of his hypocrisy.
Ugh, I wish these books would write themselves faster!
Now I’m really interested in thinking about a lot of stuff.