I'm just putting this out here because I wanted to share my thoughts and I love this story.
I understand that people that are here for the romance plot or to see the main story progressing because they don't like or simpathize with the whole Brian and Soleite backstory ,or are just nos used to slow paced and world/character building focused stories are angry at the flashback being this long , but here are my two cents.
I think (since the author has been calculating and putting a lot of effort in the detailing the current state of their world and setting up the positions each character holds in the storyline) this is no flashback frenzy , it is actually extremely important for understanding Soleite and how the world came to be as it is now and may I add it's being done faster than expected for this much of a complex plot in a really impressive and without plot-holes so that we can better understand what's to come. It's a crucial part , where we learn how this world was estabilished and how *Sol came to love humanity* , seeing as he was more than happy to not meddle and just wanted to follow the orders of his mother to not be bothered and even get her power in the process (though he had no ambition for it).
He loved Brian first , and Brian had to be that character that loves everyone , that wanted to better the place even though he only worked himself to the bone to people that used him for the sake of keeping his tribe safe , but even though he wanted to do all this alone (which is one thing he has in common with Ian) , he knew he needed help to do so and in short Sol was the one to be there for him when no one else would. Seeing such altruism and display of self-sacrifice made Sol confused and surprised , since for dragons things were resolved in power and strengh battles , and there was no need to be in society , as all-powerful capable of world building beings. He was disgusted at it at first , the way Brian did things was annoying and ineficient in his eyes but that caused him to want to undestand why he did so , why did he love humans – which is the million dollar question since he never understood why his mother loved her flawed creation so much , but it was something she in her position could never show him.
Brian is not perfect as I've seen most people saying (though he is yout typical self destructing altruistic character) , he is also a human and understands all too wel the dirt that runs free in the world and how monsters are not the only ones capable of harm. You can see that in the very begining where Brian was angry and acted rashly since he thought he couldn't change the corrupted roots of his tribe's leadership and was also being sent to his death as a sacrifice all just so he wouldn't be shown a menace to those in power. He saw in Sol an opportunity to help the people, and he also didn't want to die there. He had his many struggles but tried to handle them by risking his life and putting himself to work and he never had anyone he could trust to share the weigth of his pains with , but he deals with it in a more mature way than Ian does since he is not confused by who he is and knows what he wants , he doesn't harbour the distrust that Ian has come to know from a lifetime of trauma and a very well schemed plan of imprinting by Brixton's part and possibly a lot of meddling in timelines as I assume that he received his mother's powers instead of Sol.
Brian loving humans besides their flaws is what made Sol love him and is what opened his eyes for what love is and finally understand his mother's affection towards her creation (much like Kaworu in Evangelion , though obviously Brian is not at all like Shinji though Ian does resemble him a bit). Finally Sol decided to go against his mother all for the sake of Brian— or so we thought , he actually wanted to understand and cherish humanity since Brian did and he even told him he would not lead them lightly , having sacrificed his godhood for living in Earth as a human (half-dragon).
I would be extremely sad if the second part of this backstory was rushed since now it all comes to how the world ended up like that , separated between the two dragon brothers and why is Brian's reeincarnation so dear to Brixton now or is he merely using him to control Sol , how Sol dealed with Brian's death and how he came to be a prosperous king, why was he killed , and who killed him? There are still many questions to be answered and I think if it was anymore fast paced as it is it would ruin it for all of us and it would meddle with the story flow.
And I'm pretty sure that if this part of the backstory was used as a prequel we wouldn't understand the main plot , it was probably put in the middle of the main story because we *need to know* what happened for the gran finale. Plus if all of this was put before the actual story began I just know most readers would have dropped because of the sudden change since it's basically two different worlds and the main story is still the focus of the author , this is no random flashback , this was needed as it is and it was in right timing. Most people are just not here for complexity and great storybuilding and that's fine everyone has their tastes and I know the attention span of most people today is really short lived. Not hating on anyone , I just thought I'd share why I think it's flowing in a good pace. I have high expectatioms and up until now I have not been let down yet.