First and foremost, there was Arya’s encounter with Melisandre back in season three. While with the Brotherhood without Banners, the young Stark grabs the Red Woman, who delivers a very meaningful prophecy: “I see a darkness in you. And in that darkness, eyes staring back at me. Brown eyes, blue eyes, green eyes. Eyes you’ll shut forever.”
Another foreshadowing came when Ayra first received the Valyrian steel dagger that was used to kill the Night King. Although it seemed odd at the time, Bran gave her the dagger – first seen in a failed assassination attempt on Arya’s brother – in exactly the same location where the Night King was eventually defeated.
It’s also the same spot where the White Walker chief was created by the Children of the Forest thousands of years earlier.
Bran gives Arya the blade in the Godswood that kills the Night King! He knew what was coming! This show is incredible pic.twitter.com/0JTvkJhMCv
Even within the Battle of Winterfell itself, there were big clues, such as when Beric pulled The Hound back into the fight with a line that foreshadowed Arya killing the Night King – aka Death himself.
Sir Beric gave us the ending when he yelled at The Hound.
This was similar to a line Melisandre told Arya just before the Night King’s fall at Winterfell. Echoing the words of swords master Syrio Forel from the very first season, she said: “There is only one thing we say to death…” To which Ayra replied, “Not today”.
The purpose always been protect Arya Stark until this last moment; Ser Beric Dondarrion, Melisandre, the hound, Thoros of Myr, Theon Greyjoy even Syrio Forel.