Secrets Not Revealed

I can think of a couple "secrets" that were kept from one character or another. One would be that Jumong never finds out that Daeso was the one to create the explosion at the iron chamber in the beginning of the series. Another lesser one was that priestess Mau Ryoung never told anyone that Jumong and friends infiltrated BuYo to meet with Ye Soy Ah. Were there any other significant "secrets" that were never revealed to a character?