Alys Karstark

He feeds Stannis Baratheon military intelligence on how to capture northern castles.

He interferes in northern aristocratic politics by arranging a marriage between Alys Karstark, a northern noblewoman fleeing her abusive relatives, and a wildling chieftain named Sigorn, creating a brand-new noble house to secure wildling loyalty.

He is operating as an independent monarch, and this inevitably draws the wrath of the Boltons, the sadistic flayed man family that currently rules Winterfell after betraying the Starks.

Jon receives a horrific piece of parchment known as the Pink Letter.