Game of Thrones season 8 episode 3 "The Long Night" showed that Arya Stark is one fearless assassin who can kill anyone if she sets her mind and heart to it. After the battle at Winterfell, fans are now wondering whether she will go on a hunt to kill Cersei Lannister or would she stay in the North and try to bring everything back to order.
Arya Stark has come a long way in the Game of Thrones. The youngest Stark daughter always wanted to be a fighter and her father's death in season one made her walk on such a troubled path that she actually became a ruthless assassin. After her father's death, Arya made a list of all those people whom she wanted to kill. So far, she has killed off several but Cersei Lannister is on the top of her list and she will be definitely headed for the King's Landing to kill her.
Back in season 3, Melisandre and Arya Stark met for the first time. During their short meeting, Melisandre told Arya: "I see a darkness in you. And in that darkness, eyes staring back at me. Brown eyes, blue eyes, green eyes. Eyes sealed shut forever. We will meet again."
So far, Melisandre's prediction has come true. Arya did kill people with brown eyes and after killing Night King, she reached halfway through Melisandre's prediction. As we all know, Cersei has brown eyes and Arya will attempt to kill Cersei as well.
Furthermore, Arya Stark can become anyone as she holds the power to become a faceless man. Over the last couple of years, this fan-favorite character wore several faces and killed all those who betrayed her family members.
In the upcoming episodes, Cersei Lannister will be well surrounded by her own armies, warriors of Golden company, and Euron Greyjoy's Iron Fleet. It would actually be very difficult for Arya to walk towards Cersei and kill her. At the same time, Cersei is not a fighter and we won't be seeing her in the battleground. If it was possible, then she was an easy target for Arya.
Given this case, Arya has to become a faceless man if she wishes to kill Cersei Lannister. There are several faces which she can wear. For instance, if Cersei is not aware of Peter Baelish's death, then Arya can become Littlefinger and walk freely in the King's Landing and can easily murder the woman who once let her son, Joffrey, kill Ned Stark — her father.