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 revealed. 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.
Chapter 121: Galan brutally curb-stomps Meliodas, Diane, Merlin, and Slader, seemingly killing them all. Gowther appears and bursts into evil laughter.
Chapter 124: Fraudrin killed Liz.
Chapter 137: Elizabeth is revealed to be the reincarnation of Liz. So far, only the Druids know about it.
Chapter 141: Elaine is resurrected... by the Ten Commandments. Zhivago dies.
Chapter 153: Fraudrin reveals Gowther is one of the original Ten Commandments, and he himself is a mere replacement after Gowther lost his memories due to his Commandment curse.
Chapter 200: Gloxinia and Dolor reveal that they've been trying to take down the Ten Commandments from within, but that pales in comparison to the Wham Shot showcasing Elizabeth's first incarnation ... as a Goddess!
Chapter 203: Most of the Goddesses and Stigma are revealed to be led by a warmonger named Ludociel who is anything but holy-minded.
Chapter 215-216: Diane has regained her memories from the original Gowther and reciprocates King's love, culminating with The Big Damn Kiss. With this, King and Diane finalize their evolution into an Official Couple. And on top of this, King finally gains his wings! Lastly, Oslow is revealed to be the apparent reincarnation of Rou, a man who died protecting Gerharde because Gloxinia interpreted him as her would-be murderer. Also, Dolor's pride is the reason why he ended up joining the Ten Commandments, because it caused him to forego an obvious solution.
Chapter 221: Elizabeth encounters Zeldris who accuses her of causing Meliodas to suffer.
Chapter 222: Melascula is still alive and the real reason Elaine still lives!
Chapter 235: This chapter confirms something implied by 203. The Ten Commandments are not the strongest force possessed by the demon clan.
Chapter 241: Chandler kills Gloxina and Drole and we get the title for the next chapter: The End of the Seven Deadly Sins.
Chapter 273: Estarossa is really the missing fourth Archangel, Mael.
Chapter 299: Merlin successfully casts Chrono Coffin, stopping time around Meliodas's cocoon. However, it's too late, and matters worse, Meliodas has fully absorbed all 10 Commandments, becoming the new Demon King and growing into an adult form.
Chapter 300: It's revealed that collecting all 10 Commandments actually turns you into the Demon King's vessel, meaning that the Demon King has possessed Meliodas and completely overwhelms the Sins, Mael, and Ludociel.
Chapter 310: In the Epilogue, the Seven Deadly Sins have defeated the Demon King and Melodias has taken his body back from his father. Not only that, but Melodias reveals he now has the power to break his and Elizabeth's curses after his experiences in Purgatory. He eliminates the curses with an explosion of magic power, but unfortunately, now that Melodias has awakened his full powers as the son of a cosmic being, he is too powerful to remain in Brittania (if he does, natural disasters become more frequent and severe). In a chapter entitled "Farewell", Melodias and Elizabeth prepare to start their new lives together in the Demon Realm, they have a victory party with their friends, and Melodias officially disbands the Seven Deadly Sins. Then, as the two say goodbye to everyone and walk to the portal to the Demon Realm, rocks fall on Elizabeth, showing that her curse was still active. Next Chapter is titled "It's Not Over Yet".
Chapter 311: The Demon King was able to possess Zeldoris after being driven from Melodias's body.
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.
Vampires of Edinburgh Chapter 2: Escanor can transform the closer to noon it gets going from wimp to body builder.
Vampires of Edinburgh Chapter 3: Escanor is revealed to be able to control sunlight itself.