Chapter 25, King is revealed to be the Fairy King 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 is revealed to have been holding back his power the whole time as he demonstrates by slicing a hill with a mere branch. It's also revealed that he seems to know more about the upcoming Holy War.
Chapter 54: The nerdy looking kid Armando, was in fact Gowther the whole time. It's also revealed that he's a very effeminate looking man.
Chapter 60: The true goal of the Holy Knights under Hendrickson's faction is reveal. It's to unlock the seal of the Demon Clan just to start a war in the kingdom they can fight in.
Chapter 62: King Arthur and his huge army arrive in Liones.
Chapters 66-67: Dreyfus completely overpowers Diane and renders her incapable of fighting back. Though she is at the mercy of him and the accompanying Holy Knights, Howzer and Guila however decide to protect Diane after witnessing firsthand Diane protecting Zeal and the dishonorable lengths their superiors would go.
Chapter 70: The up to now Comically Serious effeminate-looking Gowther reveals that he has a darker side as he completely Mind Rapes Dreyfus with his ability "Nightmare Teller".
Chapters 81-82: In the midst of a battle against Gilthunder, Hendrickson, and the Masked Female Holy Knight, Meliodas attacks some sort of monster that was accompanying Princess Margaret completely hidden from sight. Though this forces Meliodas to take a hit and become wide open to an attack from Hendrickson, Gilthunder of all people comes to Meliodas' aid. It's then revealed that Gilthunder was actually forced to do vile deeds because Margaret had been taken hostage, his Badass Boast of being stronger than any of the Sins was actually a Survival Mantra taught by Meliodas to give Gil courage should he be in a desperate situation, and because said "Courage Charm" was taught by Meliodas, the latter was able to deduce that Gil was in such a situation right away way back when they reunited in the forest where Diane hid. Furthermore, Gil completely knew of the scheme to frame the Sins back then but was forced not to say anything. Gil also knew the true perpetrator of his father's murder and with Margaret safe, he releases all his pent-up wrath and completely obliterates Hendrickson.
Chapter 85: Hendrickson awakens the Demon Blood in all of the New Generation Holy Knights and turns them into Demons similar to what happened to Dale. The newly awakened Demons then start rampaging all over the capitol of Liones, devouring anyone and destroying anything in their path. Basically similar to the infamous Eclipse event in Berserk.
Chapter 93: Hendrickson is revealed to also possess the corpse of a Gray Demon for whose blood he injects into himself to become a winged satanic looking being.
Chapter 108: Dreyfus not only survived, but is revealed to be the true mastermind of all the events that have taken place (with Hendrickson simply being his Dragon. Or, more specifically, the something that is possessing Dreyfus' body is revealed to be the true mastermind of all the events that have taken place.
Chapter 109: The Demon Clan awakens.
Sidestories and other
King's Backstory: King and Diane's relationship is revealed to be actually deeper than it initially appeared to be.
Vampires of Edinburgh Chapter 1: Escanor is revealed to be a pathetically weak looking shrimp.