Ok UM backstory. But what would this achieve in the long run? How does this tie in with season 4? It is what it is I guess. I am disappointed ngl. It's not like we haven't seen him enough already in the story. Could have made a side story about how Anne got sealed and what she found out but no we got Mazino.
I wonder, or at least I hope that Siu touches a bit on his power, his weakness if he has. That could definitely then tie into Season 4, given how things ended in S3 where it seems like no family head could probably beat him, there has to be some trick to it. Especcially if he can "cancel" attacks from them, what's that trick, what's the weakness if any. If done right in the side story then it can definitely tie into the main story.
Kind of how Noblesse's author did a side story too about that "one time" Raizel stumbled upon some isolated village and it got terrorized by some bloke that used one or other crystal to power himself up...Of course that stuff appeared in teh main story, so we already had some idea about it and its capabilities...It was also a solid side story. So if done right then Siu can give us some good lore on Urek, Baek, Wolhaiksong and can also tie in whatever weakness(if any) into the main story later on.
But we'll have to wait and see what he does I guess.