'Game of Thrones' season 7 spoilers, plot news: Sansa will marry Jon Snow? Bolton ally seen at Winterfell set

A new fan theory has it that Sansa Stark (Sophie Turner) will end up marrying Jon Snow (Kit Harington), the newly proclaimed King in the North.

The theory comes from the YouTube channel Alt Shift X, which regularly publishes videos tackling the many "Game of Thrones" characters, events, twists, and speculations.

The last time viewers saw Sansa, she had just made a complete transformation, from a whiny and helpless adolescent to someone quite strong and fearless. She basically saved Jon and his army by secretly calling on the Knights of the Vale, exacted her revenge on Ramsay (Iwan Rheon) in the cruelest way, and was by Jon's side as the Northern houses pledged alliance to their new king.

However, her recent reunion with Jon, who was revealed in the season 6 finale to actually be her cousin instead of her half-brother, may soon leave fans with a bad taste in their mouths. Neither of the two know about their true relationship.

The theory presented by Alt Shift X is taken from the George R.R. Martin novel "A Knight of the Seven Kingdoms." In it, Lady Ashford, whose circumstances mirror Sansa's, has a string of suitors. According to the YouTuber's theory, if Sansa's fate continues to follow Lady Ashford's, her next suitor will be a Targaryen. Given that the only remaining Targaryens are Jon and Daenerys (Emilia Clarke), the theory suggests that Sansa and Jon will end up together.

A romance between siblings isn't exactly new in the "Game of Thrones" world, given that Cersei (Lena Headey) and her twin brother Jamie (Nikolaj Coster-Waldau) had three children together.

Meanwhile, Watchers on the Wall reports that pictures taken from the set of "Game of Thrones" season 7 reveal a Bolton man in Winterfell.

According to the outlet, actor Richard Rycroft, who played Maester Wolkan, was recently spotted in costume at the Winterfell set in Ireland.

Wolkan was the Boltons' maester in seasons 5 and 6. He was the only one to witness Ramsay murdering his father Roose (Michael McElhatton).

"Game of Thrones" season 7 debuts in 2017 on HBO.