Note: Characters are the ages they were in the show. Joffrey is 15 and Sansa is 13 when they meet at Winterfell.
"No, please don't make me go! I-I promise, I'll be better from now on!" Joffrey's green eyes were wet with tears as he implored his parents one final time to change their minds.
His mother was crying as well and hugged him tightly. "I'm sorry sweetie, I'm so so sorry..." Cersei had fought tooth and nail to stop Robert from sending her darling boy away. She hadn't been successful but at least she had managed a compromise. Instead of being sent up to be raised by Eddard Stark and the rest of those dull-witted Northern savages as the King had wanted; Joffrey would go to Casterly Rock to live with her father, his only living grandparent, Lord Tywin Lannister. It was far from a perfect situation, but at least he would be with family.
Robert looked at mother and son with an exasperated expression. "Alright, that's enough of that, both of you. Boy, I already told you, my mind's made up. You don't listen to me? Fine. But your grandfather won't be so easy on you, I'll tell you that. Tywin Lannister is not a man you want to anger; so by the Gods if you pull another stunt like the one with that poor cat under his watch…"
"That's enough Robert!" Cersei glared at her husband, her eyes red from crying all morning.
Joffrey appeared stunned that for once all his complaining and tantrums didn't get him what he wanted in the end. His face looked positively betrayed as he stared wordlessly at his father, mouth agape.
Robert was unmoved. "Well boy, It's time to go."
And so, with his Sworn shield, Sandor Clegane, called "the Hound" and accompanied by the Kingsguard, Joffrey rode into the west, to where his grandfather was Lord...
Note: Yeah, I know this was short. But it's only a prologue meant to show the divergence from canon. Subsequent chapters will all be longer than 1,000 words. Hopefully around the 3k - 5k range. Also, next chapter will skip ahead 5 years to Joffrey having just returned from Casterly Rock and the Royal family arriving at Winterfell. Joffrey's time with Tywin will be shown through his changed character as well as conversations between the two and maybe flashbacks later on.