Hoops
The Origin Flame didn't need to be explained. As far as Ryu understood it, it was the Origin of all Fire and capable of ruling them all. It was because of the Origin Flame that Ryu's Bloodline Flames awakened so quickly and also why his Flame Inheritances also progressed so quickly. Well… Until it was that his Origin Flame hit its limit and could no longer progress any further. This was to be expected, though, considering it was just an incomplete Embryo.
Still, despite being an Embryo, the docile Origin Flame was perfect for this. All Ryu had to do was to incorporate a bit into each Divine Mark. However, because it was an Embryo, Ryu still had to take things a step further to ensure that there would be no problems.
What was the core of leaving the Impose Realm and entering the Ruler Realm? Wasn't it characterized by Ryu being able to take control of his Impose Barrier and change its form?