This video (original version was created on August 23, 2018) is more about why Sansa didn't tell Jon about the Knights of the Vale. She didn't tell him because she didn't trust Baelish nor Jon's decision making. Sansa knew who Ramsay is, and she would not risk telling this information to Jon knowing his "brother" would be careless against Ramsay's battle plans. She may also be certain Jon would not accept the help from the guy who sold his sister to the Boltons. As for Littlefinger, he had planned about the battle in Winterfell long before when Stannis was going to attack the Boltons. His plan (telling to Cersei) was to wait for the two sides to battle each other until one is victorious. This is the definite reason why the Vale army had arrived late or came at the nick of time when the Boltons were unprepared.

Peter Baelish wanted himself to be the Warden of the North, but in order to achieve that, he needed either the Starks to win against the Boltons (for Ramsay would surely not give him that title) or the Boltons to defeat the Starks (with Cersei's promise). He definitely chose the Starks side due to Sansa. He was confident that if he helped Sansa, she would be proclaimed to be the Queen in the North, and his plan to take Winterfell will be to marry her or be rewarded for saving the Starks army. What he didn't expect and miscalculated was the Northern Houses and Bannermen chose Jon Snow to be the King in the North.

The second half of the video is about the future of House Stark, especially the foreshadowing and hints of Sansa becoming a Queen someday. Cersei's prophecy was foretold that there will come another, younger and more beautiful, to cast her down and take all she hold dear.

My interpretation was that Cersei loved all her children, but Joffrey was the one she held dear, mostly. And Sansa was the sole responsible of his death, unknowingly, once she told Lady Olenna and Margaery that "Joffrey is a monster." This gave the Queen of Thorns (and Littlefinger) a plan of conspiracy to poison the King and maybe put a blame to Tyrion. But that's just a theory/interpretation about the prophecy, which may not be true at all, just like many prophecies have turned out.


[My original description from the old video]
I made this video to show Sansa's prudence (her cautiousness of the future of House Stark) and her true intentions of why she lied to Jon (his honor was bound to make stupid mistakes—mistakes that both Ned and Robb lost their heads for it) and why she had kept the information about the Knights of the Vale. "Only a fool would trust Littlefinger."

Petyr Baelish's original plan was to attack the remaining forces of Stannis or Roose at the last second: "Let [them] battle. Let the enemies slaughter each other, and when they're done, sieze Winterfell from whichever thief survives." This is why the Knights of the Vale showed up very late intentionally. It was Littlefinger's brilliant plan.

(Please watch the video first before reading this.)

Regarding Cersei's prophecy:
"You have to leave home, you have to leave me, and so would you." —Catelyn

"You left your home to come here, and I'd be queen someday. Please make father say yes. Please, please. It's the only thing I ever wanted."
—Sansa (S1E1)

"Yes, you'll be queen for a time, and comes another... younger, more beautiful to cast you down and take all you hold dear."
—the witch (S5E1)

The casting you down and take all you hold dear: It's all about Joffrey. Cersei loved her children, but not as much as Joffrey. (Same reason Catelyn pleaded emotionally for Robb's life: He's my son. My first son.)

Sansa was the sole responsible for his death. Not literally, but the product of it. Remember the scene where she met the Tyrells. She told the Queen of Thorns while sobbing, "He's a monster." That directly gave Lady Olenna a motive for killing Joffrey. To protect her granddaughter. Margaery was a red herring. (Tricky George RR Martin.)

Sansa will be queen at the end, whether in the North or the Seven Kingdoms—either way, she will be Queen. (These are merely speculation/prediction; I'm quite adamant these things will be wrong.)

#GameOfThrones #HouseoftheDragon #Sansa #JonSnow