With only two Game of Thrones episodes remaining, some major deaths and some major betrayals are surely coming sooner rather than later. That involves pitting fan favorite against fan favorite, unfortunately, and one popular theory is that Arya will kill Daenerys on Game of Thrones. It would be quite the twist, and the groundwork may already be in motion.
During the Battle of Winterfell, Melisandre reiterated to Arya that she would close "brown eyes, green eyes, and blue eyes" — with emphasis on the latter, thus giving Arya the confidence to kill the icy blue-eyed Night King. Fan theorists instantly took to the internet to predict that the "green eyes" in Melisandre's mini-prophecy referred to Cersei Lannister. The facts are these: actor Lena Headey has green eyes, Cersei was one of the first people to make Arya's list, and Arya just hopped a horse to King's Landing to take care of some unfinished business.
However, Daenerys Targaryen/Emilia Clarke also has green eyes. So the Mother of Dragons could fulfill that bit of what Melisandre promised as well. Granted, neither Cersei nor Daenerys have been particularly known for their eye color on Game of Thrones — they're not Harry Potter, or anything. However, this does poke a hole in the green eye/Cersei theory and open up another possibility. And, as one Reddit theory points out, if Arya shot Daenerys with an arrow, it would nicely parallel Ygritte's death. Poetic justice, and all that.
Another reason we may want to consider this theory: we don't know what in Westeros it is that Sansa and Arya have planned. One minute, they were at a family meeting and learned that Jon Snow is a secret Targaryen. Next, Arya was high tailing it out of there on a mission. However, if Sansa sent Arya to kill Cersei while she stayed home, why did she tell Jaime Lannister that she had hoped to be there for the execution? Could they be planning to murder Dany and protect their brother instead? They definitely don't like her very much.
On the other hand, "unfinished business" doesn't exactly describe Arya's relationship with Daenerys. For the most part, Arya has no qualms with the Mother of Dragons. She's thankful that Jon got her and her troops to Winterfell to take on the White Walkers. She's pleased that Gendry was legitimized as a Baratheon by the Queen. Her only real concern with regards to the Targaryen Queen seems to be Jon's loyalty to House Stark.
Then again, maybe Arya will try to kill Daenerys, and won't be successful. As much as we love Arya, and respect what her training has made her capable of, she's bound to make a mistake at some point. Plus, sigh, if Jon Snow is destined to be Azor Ahai or whatever and needs to kill Daenerys to become said savior or whatever — Arya dying as a result of an assassination attempt would be one heck of a motive. There's even a theory on reddit that Arya is Lightbringer, the weapon that will bring about this prophecy and is plunged through the heart of the savior's true love. Yikes.
While Daenerys hasn't gone full Mad Queen yet (she's made plenty of leadership errors in her time but is pretty justifiably angry at this point, not incompetent), she does have some enemies in Westeros and her death is more than on the table in the final two episodes. Her journey to the Iron Throne may be cut short before Game of Thrones is over. Ideally, you know, nobody would die, but don't count out a bait and switch coming with Arya just yet.