[Knights of the Vale Encampment - Littlefinger's Tent]
He had just finished reading a letter that his attempt had failed, when the entrance to his tent opened.
A young girl entered, carrying a tray.
He didn't want to risk outing that he knew Arya Stark was alive and in King's Landing, especially if this was a test of his loyalty.
Instead, he watched her reaction to him, and waited to see if she would remove her face.
After about a minute, the girl reached up and in fact removed her face, revealing Arya's.
"Ah, what can I do for you?"
"How about warning me about the giant brute standing outside her chambers."
"Oh, that. That is Ser Robert Strong."
"Don't lie to me. There's only one man that large in Westeros."
"I'm not. The Mountain was killed by Prince Oberyn."
"You expect me to believe that Ser Robert is not Gregor Clegane, but another man of similar stature, who has nevr been mentioned? You can't exactly hide an eight foot tall man."
Shortly after leaving Littlefinger's tent, Arya had disguised herself as a serving girl, which would allow her to move more freely throughout the Keep. Servants were invisible.
She made her way towards Cersei's chambers, but was temporarily stopped in her tracks at the sight of a guard who closely resembled The Mountain, at least in stature.
She wasn't stupid. She knew Cersei would have guards, especially now that she was Queen. But, what she didn't expect was one of them to be a man people believed to be dead.
"I don't expect you to believe anything," he said. "In fact, if you don't expect, you'll nevr be disappointed."
"No, if I nevr expect, I could be killed."
"Yes, that too. Unfortunate your father did not possess that same wisdom."
"Don't talk about my father," she growled.
"Sorry. Sore subject. I didn't peg you as someone who gave up so easily-"
"Did I say anything about giving up?" She asked.
"Well, no. I just thought-"
"That I'm just some little girl in over her head. That's exactly what you think of me, isn't it?"
"Not at all. I only know Lady Sansa would not wish any harm to befall her sister."
"And it won't. Not unless you are the one behind it." She leaned closer. "If you even think of betraying my family, I will kill you, do you understand?"
Littlefinger nodded. "Yes, I understand."
"Good. Because you wouldn't even see it coming. Here, I could be anyone, or no one." She stood straight. "Now, if you'll excuse me, I have a Queen to deal with."
If she couldn't kill Cersei, she would make her believe she was going insane.
She had not only learned to fight in Braavos. She had also been exposed to numerous poisons, including one that induced hallucinations.
Again, she donned a new face and snuck her way into the Red Keep, making her way to the kitchens.
She was stopped by a guard. "You! Serving girl! The Queen requests wine. Fetch it for her."
This was perfect. She could slip the tonic into Cersei's wine and watch as she slowly lost her mind. It would also make her more vulnerable and easier to kill.
She approached a women, who did not appear to be occupied. "Excuse me. One of the Queen's guards requested I fetch her wine. Could you please show me where it is?"
The woman looked her over, as if she was trying to place if she had seen her. "You're new."
"Yes, I just started."
"Very well. Follow me."
Arya followed behind the woman as she led her to a wine cellar.
It appeared the woman knew exactly what she was looking for. She headed straight to a specific section, picking out a bottle. Arbor Gold.
"Fetch a pitcher and you're good to go."
Arya heeded her advice, grabbing a nearby pitcher, watching as the woman uncorked the wine, pouring it.
"There, now you can bring it to the Queen. Carefully."
Arya nodded, holding the pitcher with two hands and making her exit.
When she was out of sight, she ducked into an alcove, producing a vial and pouring it into the pitcher. Thankfully, it was also tasteless.
Satisfied, she tossed the vial out an open window as to rid herself of evidence.
Then, she continued on her way to Cersei's chambers.
Once again, "Robert Strong" was guarding the entrance, so she walked up to him and paused.
"I've brought the Queen's wine," she told him, trying to hand it to him, but he didn't move or speak.
"He doesn't speak," a voice behind her said.
Arya turned around to see who it was. The woman who'd helped her gather the wine. Only now, she was carrying a tray of food.
"Her guards returned and she requested something to eat."
"What do we do? Leave it here?"
"No, no. You've stated your purpose and he has made no moves to block you. You are free to proceed with delivering the Queen's wine, just as I am to deliver her food."
Arya nodded and the two of them began ascending the stairs, without protest.
She knocked on the door, hearing a "Come in."
Both of them entered the room.
"Ah, good, my meal and wine." Cersei said. "I assume it has been tasted?"
Arya could help but notice how different Cersei looked from the last time she saw her. Her hair was cut extremely short, shorter than Brienne's and her features had grown harder, somehow.
"Yes," the woman beside her said.
They set the wine and food on her table, curtsying before exiting.
Later that night, Arya returned and snuck into Cersei's chambers.
She had read of the infamous tunnels built by King Maegor the Cruel, and began searching for one that led to Cersei's room. After a few close calls, she had found one.
When she entered, she noticed the pitcher was empty. Good, the hallucinogen should still be in effect.
She had dressed herself in a short blonde wig, the approximate length she had remember Joffrey's as being.
With it, she wore a red and gold tunic; Lannister colours. On her head, a crown she had "borrowed", and on her face dried blood.
"Mama, mama," she called. "Mama."
Finally, Cersei shifted awake.
She squinted, look at Arya's form.
"Joff-Joffrey. How?"
"They killed me, mama. They killed me."
"Oh, my sweet boy."
Arya had to resist the urge to roll her eyes. Joffrey was many things, and sweet was not one of them.
"I'm so sorry I couldn't save you."
Tears began streaming down Cersei's face. If it were almost anyone else, Arya might have felt bad, but this woman and her family were the reason so many members of her family were dead.
"It hurts, mama. It hurts."
"Don't worry, my sweet boy. Your father has killed the person responsible for your death. You have been avenged."
"Avenged?! I'm dead!"
"I know, I know-"
"Your Grace, are you alright?" A guard called from outside the door.
"I need to go."
"Don't leave me Joff-"
"I must!" She began walking away as Cersei started shouting, turning her brisk pace to a run.
She had just entered the hidden passageway, and closed it behind her when she heard the door to Cersei's chambers burst open.
Cersei could be heard crying and shouting about her "Joff".
But, Arya didn't stick around to risk capture.
She had done what she come there to do, at least that night.
Cersei still needed to die, and Arya would make sure it was by her hand.