The Starks are back in Winterfell and what should have been a happy reunion of the siblings has turned into a political battleground for Petyr Baelish.

Source: theturnertalks

Jon Snow has left Sansa incharge of Winterfell and Baelish is under the impression that he can manipulate her, as he has done numerous times in the past. 

Littlefinger tried to impress Bran Stark in the previous episode, but after the "Chaos is a ladder" conversation, he knows it's better if he stays away from Brandon.

Source: indiewire

Littlefinger gifted his precious Valyrian steel dagger to Bran. Bran passed it on to his sister Arya which raised Littlefinger's eyebrows.

Source: collider

Arya, who spent a long time getting trained as no one, has never met anyone as clever as Littlefinger. This week, when she started following him around the castle, little did she know that she was just picking up the crumbs Baelish had laid down for her.

She follows him around and finds a note that was written by Sansa back in Season 1.

Source: Independent

Here's what the note says:

Robb, 

I write to you with a heavy heart. Our good king Robert is dead, killed from wounds he took in a boar hunt. Father has been charged with treason. He conspired with Robert’s brothers against my beloved Joffrey and tried to steal his throne. The Lannisters are treating me very well and provide me with every comfort. I beg you: come to King’s Landing, swear fealty to King Joffrey and prevent any strife between the great houses of Lannister and Stark.

Your faithful sister, Sansa

To give some context, Sansa was forced to write this note after Ned got arrested for treason. Cersei tells Sansa to write this letter and gives her false hope that she could possibly save Ned by writing it. When Cersei along with Varys forced Sansa to write this letter, Petyr Baelish was in the room as well.

Watch the scene here:

But why is this note relevant again?

Baelish believes in ensuing chaos. 

With Sansa, he has already established a sense of control and he can clearly see a little wedge developing between the Stark sisters. By planting this note, he probably plans to divide Arya and Sansa so they can be occupied in their quarrels and he can control Winterfell, and eventually, the Iron Throne.

Arya can misinterpret this note as it makes Sansa sound like someone who betrayed her father but we're hoping that Arya will judge the situation better than Petyr expected.

The next episode's preview surely hints at some tension in Winterfell and this note will probably play a role next week as well.