Spoiler Alert! Massive spoilers ahead for Game of Thrones season 8 episode 3 and earlier episodes.
Game of Thrones Season 8, Episode 3 took the audience by surprise when the winning blow was given by amazing Arya Stark. While many considered this anticlimactic, here's how the show had been building up to this moment all along.
1. When Arya Stark was introduced to the audience as a skilled marksman.
When we first meet Arya, she's at the Winterfell courtyard outperforming her brothers with her archery skills. This moment establishes how being a skilled fighter is a huge part of her identity and will come to play later on.
The scene shows how her skills are better than the others (boys or girls) even before any training whatsoever. This possibly foreshadowed how she, in fact, would emerge as the final victor leaving every other 'lesser' fighter behind.
2. When she says, "that's not me".
Unlike her sister, Sansa, Arya never wanted to be and remain a noble 'lady'. When Ned Stark has a heart-to-heart conversation about her eventually becoming a lady of a noble house, she immediately refutes saying "that's not me".
There are obviously bigger things in store for this little badass. And simply being a political figurehead is not one of them.
3. Her training in water dancing.
Long before she trained to be a deadly assassin, Arya was groomed in the Braavosi water dance sword fighting technique. She was taught by one of the greatest teachers from Braavos, Syrio Forel who also gave her the winning words of the Winterfell battle.
4. "What do we say to the God of Death?"
Arya's cryptic sword teacher, Syrio dropped several pearls of wisdom as they trained. One which stayed on with her and the audience alike was this:
There is only one god and his name is Death, and there is only one thing we say to Death, Not today.
Followed by many other times when Syrio asks her "What do we say to the God of Death" to which she replies, "not today".
This not only gets referenced by Melisandre in the episode, it also reflects how the Night King is a literal embodiment of a 'God of Death' and that they cannot let him win today.
5. The blue eyes she'll shut forever.
When Arya meets Melisandre in season 3, she senses a 'darkness' in her. She then prophetically tells her that in her she sees brown eyes, green eyes, blue eyes, and eyes she'll shut forever.
While many thought this was a reference to her changing faces and thus eye colours, it actually alluded to the people she would kill. Several of her victims have had brown eyes, but this time it was the 'blue eyes', referring to the Night King, that were going to shut forever.
6. Her time with The Hound.
When Arya is 'kidnapped' by The Hound, he becomes an unlikely teacher who gives her valuable combat lessons along the way. He trains her to find weak points in one's opponent, penetrate through their armour, and stab people in vulnerable spots like the heart.
7. Her training as a faceless assassin.
After her time with The Hound, Arya heads to the House of Black and White in Braavos to train as a faceless man. But even before the house trains her she already is a fierce warrior with her own skillset.
Her training here essentially transforms her into an even more lethal weapon with skills like stealth and deception.
8. When Arya turns 'blind'.
During her time in Braavos, Arya is punished with blindness for the untimely murder of Meryn Trant. This she uses to her advantage as she adapts to fighting in the dark with equal skill. Her fighting prowess is also shown when she provides the Waif with her killing blow in complete darkness — now an asset for Arya.
9. Arya's direwolf, Nymeria.
Other than Ghost, Nymeria is the only Stark direwolf who's alive and leading a wolfpack in the Riverlands. While it is not clear why she appeared on the show, it may have been to allude to Arya personality — wild yet tame, gentle yet a deadly fighter, a survivor in the worst of times, and eventually the 'protector' of her pack.
10. The Catspaw dagger.
The Catspaw dagger is a character in itself on Game of Thrones. It is what began The War of The Five Kings (after being used to attack Bran) and it is what ended The War for the Dawn.
The Valyrian steel dagger was later gifted to Bran by Littlefinger (who was also executed by the weapon) and eventually passed on to Arya (probably knowing that Arya will kill the Night King with it). It is notable that this exchange happened in the Godswood — the same place the Night King was finally defeated.
11. When Arya and Brienne were in a sparring session.
Back in Winterfell, when she is sparring with Brienne, Arya wins the fight owing to her ambidextrous fighting technique. Her unique skill of switching hands is what gives her the edge over the Night King, eventually leading to his death.
Even her outsmarting Brienne was a huge sign in itself. Brienne, who was much bigger and stronger, had defeated The Hound in battle earlier on. This showed how she was destined to eventually defeat someone who's much stronger than her.
12. When Arya displays her skills throughout her journey and when she's back home.
While she's on her way back to Winterfell, Arya annihilates the entire House Fray displaying her skill as a faceless man. Later on, she displays her skills of deception with Littlefinger, supposedly the most deceptive person in Westeros by staging a conflict with Sansa. She even executes him offering a swift killing blow to the throat — something only a trained assassin would know.
Even Jon Snow is thrown off by her stealth when she creeps up on him in the Godswood, when he's back at Winterfell. This shows how she is essentially an extremely adept ninja by now.
13. The Night King died just the way he was created.
In one of Bran's visions, we witness the Night King's creation at the hands of the children of the forest. It seems fitting that he met his end at the hands of someone who was basically considered and underestimated as a child in the GoT universe. His death also occurred near a Weirwood tree with a dagger through his heart, just as he was created beside one with a dragonglass dagger through his chest.