Il had nothing to do with Yu-Won's death, and Su-Won killed him for nothing.
While Su-Won is convinced that Il murdered his father, no one else seems to - at least, the only people we see agreeing with Su-Won all give off the impression they're simply tolerating his obsession for their own purposes. There doesn't seem to be any actual evidence in canon that Il did it. (especially since he seems to have already been named heir before Yu-Hon's death) The really interesting idea is that someone
manipulated Su-Won into thinking this, so he'd grow up to hate Il. Whether Su-Won killing Il and taking over the country himself is what the person had in mind, or whether X simply intended to sow dissent and destabilize Kouka using Su-Won as a puppet is a matter of further speculation.
- Which could also lead to a bloodless ascension to the throne for Yona at the end of the manga; Su-Won discovers the truth, and realising himself to be an unjustified kin-slayer (which was one of the most grievous offenses in medieval times, as well as most fantasy worlds) gives up the throne to Yona as penance.
- This "X" could be Kei-seok.
The Kouka royal line is under some kind of blood-lust curse. Yona is immune to it, Il has kept it under rigid control. This is why Il was so adamant about Yona not marrying Su-Won.
Granted, this goes into full-on conspiracy theory... but if the Kouka line had some kind of curse, where once you start spilling blood, you can't stop - it would explain a lot about Yu-Won and his son.
Yu-Won seemed to love war to the point of near-obsession, which might explain why Il became heir - their father might have forseen Yu-Won pursuing war to the point where he'd neglect to actually rule his country, or even worse, bankrupt it in order to fund his campaigns. (real life example: Richard the Lion-Heart, who spent so long having fun in the Crusades that he let Prince John run the country into the ground - which was also in no small part thanks to the revenue drain of funding the Crusades, AND Richard's literal ransom fit for a King. At least we got the Magna Carta and the Robin Hood legends out of it). Not to mention, empires built this way inevitably collapse when the driving figurehead dies, or within a few generations, usually leaving the original country in wrack and ruin - and if I remember rightly, something very like this has already happened once in Kouka's history. Very good reasons to keep Yu-Won off the throne anyway.
However, this theory would also explain Il's absolute pacifism, which hasn't been given any kind of reason in canon. Hak, at least, seems to have a high opinion in Il's courage - and I keep thinking of that scene in the anime where Il's smiling while refusing a fight... but Hak can see that Il's clenching his fists so hard that his palms are dripping blood.
Any kind of curse-madness of that kind would have to be kept off the throne at all costs, which is why Il won't let Yona marry Su-Won. Yona could be immune simply because she's female, or descended from a second son, or even because she's the reincarnation of the Red Dragon.Why hasn't Su-Won fallen prey to it yet? a) it's taking awhile b) he has a considerable amount of willpower, and is controlling it like Il did c) he channelled it into his hatred and revenge on Il d) killing another of your blood ends it or even e) I'm completely wrong about this whole thing.
- One problem with this theory: earlier in the manga, it's stated that different tribes have ruled Kouka at different times. On top of this, different tribes have different ways of selecting generals, so it would be impossible to tell if a dynasty would stay in power (so why curse them to begin with?). According to the manga, the Sky Tribe has only held royal authority for the past two-hundred-fifty years. King Il's father could easily have foreseen the obvious problems of having a Blood Knight on the throne (with the historical precedent mentioned) and acted accordingly without the entire blood line being "cursed."
Ik-Su and Yun are both descendants of Zeno
... that's why they both have blonde hair.
Zeno has been around for a very long time... and we know he's been married at least once. He's had plenty of time to spread his bloodline around the kingdom - the White Dragon has been descended in a direct bloodline, and Blue Dragon solely within the small gene pool of a single tribe. Also: Zeon was the first Priest of the Court, in Hiryuu's time. The last Priest of the court, Ik-Su, is also a blonde. Maybe one of the reasons that Ik-Su adopted Yun was that he knew that blonde hair meant that they were at least distantly related?
- Jossed. Kaya was too sick to have children in the time Zeno knew her and had no relationships before or after her. Ik-Su and Yun are just regular blonds.
Yona will decide not to seek revenge.
She decides she can't forgive or forget what Soo-Won has done, but killing him won't do anything but plunge Kouka into more chaos.
Yu-Hon suspected Yona was Hiryuu.
First because of her red hair. Then the priests made some sort of prediction and this would also explain why he had the priests thrown out of the castle. Make the jump from him suspecting her as Hiryuu to when she, Soo-Won, and Hak left the castle as kids and Yona got kidnapped. What a perfect way to get her out of the way so Soo-Won could be King. Which culminates in King Il killing Yu-Hon because he was a massive threat to Yona.
Soo-Won and the generals will have to cooperate with the Happy Hungry Bunch.
Things are getting a bit out of hand and the dragons' power will be necessary to stop incoming threats, so Soo Won will ask Yona for help. There will be a lot of awkwardness...
- Sorta confirmed. They did cooperate in the rescue of Lili and the other captives at the slave camp, but there was no direct communication.
Yu-Won killed Yona's Mother.
We've seen Il take a knife to the hand when Tae-Jun pulled said knife out in front of Yona. He wasn't even really threatening her, but rather was threatening Hak, but Il went from tubby and worthless to catching a knife with his hand and then ignoring the pain so his daughter wouldn't be upset. Is it that hard to think he would kill his brother for killing his wife? And to keep Su-Won safe and protect his brothers reputation he only ever said it was a "rebel" (technically not even a lie) rather than tell the cruel truth... which would mean that the cycle of revenge is more complex than it appears.
Something is wrong with the Wind Tribe.
The Fire Tribe villages had all the droughts. The Water Tribe had Nadai. The Sky Tribe had the murdered king. The Earth Tribe was in a slump with the mines, and Soo-Won went out of his way to fix it. The Wind Tribe doesn't seem to have any problems in comparison, which makes it seem as if they really do but Yona and Hak just haven't seen any yet. It probably has something to do with why there are so many orphans in Fuuga.
- Remember that Hak was the Wind Tribe's general at the beginning of the story and Mundok is still very active. Actually, the Wind Tribe does have a problem that is ongoing and has been addressed before by both Hak and Yona: supporting the rightful heir to the throne and their (now former) general to despite Kouka's shift in power.
Hak is from Xing and his parents were some of the prisoners of war Yu-Hon executed
Not only is the Wind Tribe very close to Xing's borders, but the execution happened seventeen years ago—in other words, it happened long enough ago for eighteen-year-old Hak to have been born but young enough that he wouldn't remember his birth parents.
- This could be the reason that there are so many orphans in the Wind Tribe. That is, the Wind Tribe used to have a problem with refugees. That or Mundok was too much of a softy to not take such children in. Alternatively, he could be atoning for Yu-Hon's massacre.
- Half-confirmed? Hak doesn't seem to be from Xing, but the recent fanbook confirms that Hak's parents were casualties of the War with Xing. This is the stated reason for the Wind Tribe's high orphan population as well, and cost the life of Mundeok's biological son.
King Il tried to recreate Kouka's borders during King Hiryuu's time.
The dragons get sick basically the second they step across the border, and it's likely that King Hiryuu kept his kingdom to a size in which the dragons could travel freely without health issues. The following kings conquered more land, not knowing or caring about the limitation of the dragons.
- Two problems with that: 1. Few people believe in the legend of the dragons during the period the story is set. 2. The dragon villages move and do not maintain contact with other groups.
The initiation which the dragons go through makes their power life-long like the first generation's.
The initiation described by Kija as being like his blood was running backwards also had a visible effect on his arm (the others hid it). Unlike their predecessors after the first generation, the present dragons are serving their "King Hiryuu," Yona. Also the words of the initiation seem to hint at their servitude being long lasting ("We are your other selves..." etc.). Practically speaking, this theory would make a lot of sense regarding the story and its progress.
- To add to that, the only reason that the previous dragons had such short lives was so that they would always be in peak physical condition when the reincarnation of King Hiryuu comes. People tend to slow down a bit after they get out of their 20's, and the dragon's blood wanted to make sure that when their king came for them they wouldn't be left with an old man that couldn't help much.
Hak is colour-blind.
He's not remotely suspicious of Jae-ha, despite that he has green hair and tends to disappear suddenly—while they're in Awa for the very reason of finding the "flying" green dragon warrior. He's obviously met Shinah and Kija already, and would have noticed the pattern of their hair colour matching which dragon warrior they are. Jaeha being the green dragon should have been obvious to him... unless he couldn't tell that Jaeha has green hair in the first place. This is further backed up by the fact that he's never commented on the redness of Yona's hair either. He could be red-green colour-blind specifically, which would leave him seeing both Yona and Jaeha with inconspicuously brown hair.
Zeno's power can be passed on, but it's not something he would ever do.
Zeno says that Ouryuu's power can't be passed on like the other dragons, but there's one major difference between them: the other dragons have descendants, while Zeno does not. It''s entirely possible that if Zeno had been able to settle down with Kaya and start a village with his own children, his immortality could have been passed down to them like the others. However, even if this proves to be the case and Zeno realizes it, he would never try to pass off his powers because of all the suffering he went through with them, especially not to his own kin.
Another reason Soo-Won doesn't want to marry and have kids because of his incurable illness
- There is another why Soo-Won doesn't want to marry and have kids because he will end up inherit the crimson illness that only affects King Hiryuu's bloodlines. It would mean he will rather be the last one to die and have his bloodline die out.
