A story of war, betrayal, love, and madness, HBO’s dark fantasy series “House of the Dragon” features a sprawling cast of complex and contemptible characters. But despite all the bloody backstabbing committed by sparring factions of incestuous royals, no one in the “Game of Thrones” prequel is as vociferously hated by fans as Ser Criston Cole.

Played by Fabien Frankel, Criston is introduced in “House of the Dragon” Season 1 as a handsome and humble knight whose ideals are gradually eroded by his own bitterness, anger, and hypocrisy. Criston falls off his self-imposed pedestal in Season 1, Episode 5, “We Light the Way,” when he suddenly kills Ser Joffrey Lonmouth (Solly McLeod) during the wedding celebration for Princess Rhaenyra (Milly Alcock).

While the moment that sparks the brutal beating is left unseen, Joffrey’s fate is sealed when he deduces that Criston was secretly Rhaenyra’s forbidden lover. Joffrey is in a clandestine relationship with Rhaenyra’s betrothed, Ser Laenor Valeryon (Theo Nate), and while their past and present paramours are distracted, he suggests to Criston that they should keep each other’s secrets. This imagined threat sends Criston into a rage, and he beats Joffrey to death in the middle of the banquet, crushing his skull and causing pandemonium.

Unfortunately for Joffrey, his murder isn’t even really about him, but rather Criston Cole’s seething resentment towards Rhaenyra. By his own admission, Criston owes everything to Rhaenyra, as she had personally recommended him to be sworn into the Kingsguard, which is the greatest honor of his life. Rhaenyra spends a sexually-charged night with her roguish uncle, Prince Daemon Targaryen (Matt Smith), and, feeling emboldened, seduces Criston.

Following their shared night of passion, Criston becomes increasingly guilt-stricken over breaking his vow of chastity, and he proposes that they run away from Westeros to marry. Rhaenyra refuses to abandon her duty to the crown, however, and Criston’s affection for her sours into hatred as he redirects his guilt and insecurities onto the young princess.

Their marriage arranged as a political union, Rhaenyra and Laenor agree that, because Laenor is only interested in men, they can both carry on discreet affairs. Joffrey notices Criston’s agitation at watching Rhaenyra and Laenor at the feast and, mistaking Criston’s resentment for longing, approaches him. Unbeknownst to Criston, Rhaenyra reunites with Daemon at that exact moment — she dares her uncle to elope with her, right before the chaos from the fight separates them. Ironically, Criston’s murder of Joffrey is what ensures Rhaenyra and Laenor’s marriage after all.

Viewers horrified by the sight of Joffrey’s brutalized corpse may be shocked to learn that he meets a more gruesome end in the book that inspired the television show — George R. R. Martin’s “Fire and Blood.” Unlike the other “A Song of Ice and Fire” novels, “Fire and Blood” is presented as a historical record of House Targaryen, and it collects reports from multiple — and often conflicting — sources. In the book, it is unclear if Rhaenyra and Criston consummate their relationship, or who ultimately rejects who. Nevertheless, Criston still kills Joffrey.

In “Fire and Blood,” Criston and Joffrey joust in a tournament at Rhaenyra and Laenor’s wedding feast. When he sees Rhaenyra give her garter to her suspected lover, Harwin Strong, Criston flies into a “black fury” that he unleashes on the other challengers. Criston savagely beats Joffrey with a morningstar, and the mortally wounded knight dies after six days of suffering, with Laenor at his bedside. 

In this version of events, Joffrey is an innocent bystander and doesn’t even make the mistake of approaching Criston about his affair — and without the excuse of a misunderstanding, Criston’s murder of Joffrey becomes even more unforgivable. Regardless of the source material, the fact that Criston is still able to serve in the Kingsguard, and eventually ascend to the powerful position of the Hand of the King, is one of the most glaring mistakes of “House of the Dragon” Season 1.