Chapter 25, King was revealed to be the king of the fairy's 700 years ago by Elaine.
Chapter 28, Meliodas is hinted to be extremely dangerous via his shadow.
Chapter 29, Meliodas is revealed to have destroyed the Kingdom of Danafor in the past when he lost control.
Chapter 30, The Demon Ban killed in his backstory is being used to empower the second generation of Holy Knights.
Chapter 32, Elizabeth is revealed to have come from the Kingdom of Danafor that Meliodas destroyed.
Chapter 51, Meliodas revealed that the whole time he was fighting, he was holding back his power to which he shows by cutting a small mountain with just a branch he found and he know more about the upcoming Holy War.
Chapter 54, the nerdy looking kid Armando, was in fact Gowther the whole time and he had a girly looks as well.
Chapter 60, We find out there's another princess being hidden away and she knows full well the Holy Knights are the ones causing trouble. What's more we finally get the true goal of the Holy Knights, to unlock the seal of the Demon Clan just to start a war in the kingdom they can fight in. Yeah that seems like a great idea.
Chapter 62: King Arthur and his huge army arrive in Lyonesse.
Chapter 73 King and Diane spent five hundred years together before he erased her memory.