2. Sansa The Traitor
In the book and series Sansa Stark, due to her association with a House deemed traitorous to the Iron Throne, is cast aside as the prospective bride of Joffrey Baratheon - in favour of the more politically suitable Margery Tyrell. Sansa escapes Kings Landing due to the cunning (and amorous intentions) of the ever-resourceful Petyr Baelish Littlefinger. Littlefinger doesnt feature in the initial plot outline, and Sansa remains in Kings Landing, where she abandons her family in favour of Joffrey and House Lannister, ultimately becoming pregnant with his child. As GRRM states: she will bear him a son, the heir to the throne, and when the crunch comes she will choose her child over her parents and siblings, a choice she will later bitterly rue. Considering he destroys all rivals and heirs in order to take the throne, the Jaime Lannister of this iteration probably kills this child. Interestingly, Sansas betrayal of House Stark is mirrored by Tyrions own betrayal of House Lannister as he becomes increasingly dissatisfied with his own family. This fits well with GRRMs love of opposing dualities (ice vs fire, summer vs winter, etc) and may ultimately have been triggered by what was his love for Arya. This love results in a deadly rivalry between Tyrion and Jon Snow.