This is a guess, but I think Ryeong had taken care of childre(?), ghost(?), other entities besides black hair dude. So like he was prab refering to the children before black hair dude
in the first chapter
one of his adopted kid turn disciple (all human btw, jae is the first nonhuman) decided to call him father and I think ryeong also considered him as his son (as mentioned this latest chap)
I really have to re read this manhwa from the beginning lol thx!
I see thx!
SON WHAT SON! Since when was it ever mentioned that Ryeong had a son?!