Responses
Yes, he's probably a foreign prince or related to some foreign royal family (he could be a bastard).
That also would explain his value as a slave and possibly explains why he was first got hired by royalty and he may not even know it. And if anything it would legitimize his relationship with master Jin even if he is a bastard child his blood is still valuable, great theory.
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I reread the part with the fortune teller when she talks about nine kings were bestowed with a great power through their blood.
This line is important:
"She prevented the dragons from existing in their complete forms unless they drank the king's blood".
And Jin asks, "Were their cases where kings and dragons failed to coexist?"
And baby dragon answers, "Yes, when were curses were called down for a long time".
We know that Jin's blood is cursed and the baby dragon can't eat it like he's supposed to.
The dragon didn't know who he was until he saw Sul. Furthermore, how is able to take on his complete form when that's impossible without drinking royal blood.
Sul has shown no ability of regeneration, YET baby dragon has been able to take on his adult form. Is that adult form his complete form? Or just a halfway complete form?
The dragon has said he'll become one with Sul. Sul is his intermediate to be able to absorb the regeneration. I wonder why Sul.
I wonder if Sul has connections to the bloodlines of one of the other nine kings.