Since her escape from Winterfell and Ramsay Bolton, Sansa Stark has become the complete opposite of what she used to be.
From a helpless, unlucky and dumb girl she has suddenly turned into a ferocious, smart and ruthless one, who will stop at nothing till she avenges her father’s death and get the Starks back on their feet.
After seeing their attempts to seek allegiance from the houses getting failed, Sansa behaves like a sneaky little girl and writes a letter to someone asking for help. Its not clearly visible to whom is the letter addressed, but some zoom-ins and Photoshop Skills one Redditer CreepyPancakes was able to decipher the actual message.
So, it seems that Petyr Baelish’s words seem to have done their magic again. Sansa is asking Littlefinger to send the troops from Vale against the Boltons in return of some reward. Sansa’s sheer determination to win this battle by any means possible can actually help Jon Snow defeat Ramsay’s army. Way to go girl.