Bran as the Night King Is the GoT Twist We Needed But Never Got
This theory is more in line with Martin's books than the show itself.
Based on the deep, complex, and multifaceted stories by George R. R. Martin, HBO's Game of Thrones failed to capture the essence of the author's original fantasy world. Of course, the adaptation was visually striking and fascinating to follow for most of its run, but the last two seasons were a huge bummer for fans, bringing the story to a less-than-satisfying closure.
Following Martin's general guidelines for the finale, the series' writers ruined some of the characters' arcs, and Bran Stark and the Night King were the ones who suffered the most. Many fans note that the Season 8 finale downplayed Bran's entire story of learning from the Three-Eyed Raven, and the Night King was killed by Arya without any impact.
While the show ended more than four years ago and Martin still hasn't finished the final book in his novel cycle, fans are free to theorize and come up with more entertaining conclusions for the beloved characters. Perhaps one of those theories may serve as inspiration to the author himself!
'Envision this: Bran's unparalleled warging abilities leading him to the distant past, where he becomes unintentionally trapped in the body of the First Man transformed into the Night King by the Children of the Forest,' a GoT enthusiast shared an intriguing theory.
The Night King is an original creation by the show's writers, but the 'Night's King' is mentioned in one of the books — he is a legendary commander of the Night's Watch who lived hundreds of years ago and committed brutal atrocities while making sacrifices to the White Walkers. Bran also said that the Night's King was a Stark of Winterfell, and perhaps his name was also Brandon.
So if Bran turned out to be the Night King, this would add more tragedy and complexity to the whole story, showing how well-intentioned actions can lead to dire consequences due to selfish passion and lack of mindfulness.
In this reimagination, Bran's powers would flourish, leading to his immense control over time and space. Ultimately, the character's efforts to rectify past mistakes and prevent the White Walker menace would pave the path for him to become the very beast he sought to thwart.
Who knows, maybe Martin himself came up with a similar idea while writing the never-ending The Winds of Winter? In any case, it looks like the author should pay attention to fans' theories online because some of them are pure gold and worth being adapted as an alternative short story at least.
Source: Reddit.