Some fanfictions might focus on an alternate universe where Joffrey is not a king. He could be a simple knight, and the story could explore how his personality would develop without the power and privilege of the throne. He might learn humility and honor in a different way.
In some fanfictions, Joffrey is re - imagined as a more sympathetic character. His cruel actions are often explained as a result of his upbringing and the political pressures around him.
In a fanfiction, the lemon could play a magical role. Imagine Joffrey is cursed, and the only way to break the curse is through a lemon - related task. This could lead to a whole new side of Joffrey being explored as he has to rely on something as simple as a lemon to save himself.
One interesting scenario could be that it was actually a planned assassination by a secret alliance of the Starks and the Tyrells long before the wedding. They worked together in the shadows, using Sansa as an unwitting pawn. The Tyrells provided the poison, and the Starks had someone in place at the wedding to ensure Joffrey drank it.
One interesting scenario could be a rewrite of their relationship where Joffrey is secretly influenced by a more benevolent force. This might lead him to treat Sansa with more kindness than in the original series. Maybe he starts to see the value in having an ally in Sansa rather than just using her as a pawn.
One idea could be an OC who is a healer in King's Landing during Joffrey's reign. The OC secretly tries to undermine Joffrey's cruel rule by using their medical knowledge to help those he persecutes. They might start by treating the families of those unjustly imprisoned. This could lead to a dangerous game of cat and mouse with Joffrey and his cronies as they suspect someone is working against them.
Joffrey is often characterized as even more cruel and unhinged in fanfiction. His violent outbursts and lack of mercy are sometimes exaggerated. Margaery is usually shown as a very intelligent and manipulative woman. She uses her beauty and charm to her advantage.
One possible fanfiction could be about Joffrey's brother Tommen growing into a wise and just ruler. He could be shown learning from the mistakes of his older brother. He might start secretly training in combat and political strategy, with the help of some of the more noble characters in the series, like Tyrion perhaps. He could then start to make changes in King's Landing, trying to reverse the chaos that Joffrey had caused.
One idea could be an OC Baratheon who is a long - lost cousin. This OC could come to King's Landing with a claim to the throne, causing political unrest among the existing Baratheon claimants. He or she might have unique skills, like being an expert in naval warfare, which was important for the Baratheons. Another plot could involve an OC Baratheon woman who disguises herself as a man to fight in the wars, and along the way, she discovers secrets about her family's past that could change the course of the Baratheon legacy in Westeros.
One possible fanfiction could start with Robert Baratheon as a young man. He is full of ambition and dreams of a united Westeros under his rule. He trains hard in combat, his sword becoming an extension of himself. He meets his future friends, like Ned Stark, during these formative years. They share tales around the campfire and make grand plans for the future. As he grows older, he participates in battles, his victories making him more and more renowned. His charisma draws people to him, and soon he is seen as a natural leader. But with power also comes temptation, and he has to face the challenges of politics and intrigue that come his way.
One interesting fanfiction could be one where Renly Baratheon survives and forms a different alliance. Maybe he teams up with the Starks against the Lannisters, which would completely change the power dynamics in Westeros.