@Rozzak I don't really think you understand what is going on in the story right now. The people of the kingdom LIKE soo-won, they don't know that he killed the previous king. He has done good things for the kingdom so far and that's all the citizens care about. On the other hand, people don't know anything about Yona. They may even see her as a spoiled brat. Also, it's not in Yona's character to become queen in the way you have described.
Anyways, if you remember, Kija has said something along the lines of not being able to hate soo-won in the past chapters. Honestly, that's how I feel about him too, I can't really hate or like him. Yona doesn't have the upper-hand, along with the dragons. They are basically prisoners disguised as "special guests". If Yona steps out of line, that dumb advisor would probably not hesitate to do something to the dragons/Hak. And if the dragons/Hak step out of line, yeah...vice versa.
You should probably just wait for what happens, I think the story is going perfectly well so far. If you're not enjoying it, then drop this story lmao.