Perhaps an OC who is a skilled warrior from a small, previously - unheard - of tribe. They join Daenerys' army and teach her troops new combat techniques. For example, they might introduce a form of guerrilla warfare that gives her an edge in battles.
An interesting OC could be a young seer who has visions of Daenerys' future. This seer tries to guide Daenerys, but their visions are often misinterpreted, leading to some interesting plot twists and moral dilemmas for Daenerys.
One idea could be an OC who is a healer from a far - off land that Daenerys meets during her travels. This healer has unique knowledge of magic that could help Daenerys in her quest for the Iron Throne.
Another fanfiction concept could be a 'what if' scenario. What if Jon was the one who found Daenerys when she first landed in Westeros? This would put Jon in a position of power and knowledge about this new queen. He could act as her guide through the complex web of Westerosi politics. Their relationship might develop more organically as he helps her navigate the land he knows so well, and perhaps they would fall in love more gradually, away from the prying eyes of the other lords and ladies.
An interesting 'oc game of thrones fanfiction' could focus on an OC who is a female knight in a world dominated by male warriors. She could face discrimination but also prove herself in tournaments and battles. Maybe she becomes a trusted ally of a major character like Jon Snow. Or you could have an OC who is a bard that spreads tales which either inspire or deceive the people of Westeros. Also, an OC who is a foreign diplomat trying to broker peace deals between the warring factions while having their own hidden agenda would be a great concept.
One idea could be to explore his upbringing in a world where his mother has conquered Westeros. He could grow up with a strong sense of justice, influenced by Daenerys' ideals. Another could be his relationship with the dragons. Maybe he has a special bond with one of them that is different from his mother's.
One plot idea could be that Daenerys and Arya meet on the road. Arya, being the assassin she is, is initially suspicious of Daenerys. But as they start talking, they realize they both have a common goal of bringing justice to Westeros. Daenerys offers Arya a position in her court, which Arya hesitantly accepts. Together, they plan to take down the corrupt lords and make Westeros a better place.
One idea could be an original character who is a bastard from a minor noble house in the North. They grow up with a unique skill, like being an expert tracker. They could get involved in the events related to the White Walkers early on, perhaps by accidentally stumbling upon one of their lairs. Their journey could then be about warning the other houses and trying to find a way to stop the threat before it reaches the major kingdoms.
One plot idea could be an OC who is pregnant and trying to hide it from powerful enemies in King's Landing. She has to navigate the dangerous political intrigue while protecting her unborn child.
One idea could be an OC who is pregnant and is trying to hide it from the warring factions in King's Landing. She might be a servant in the Red Keep and is afraid of what will happen if her pregnancy is discovered, as she doesn't know who the father is among the many lords and knights who frequent the castle.
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.
Perhaps the OC Dragonlord is a bastard of a Targaryen. They grow up in Essos, learning the ways of dragon - taming from an old sorcerer. When they hear of the chaos in Westeros, they decide to cross the Narrow Sea with their dragon, planning to claim a throne for themselves. Along the way, they form an unlikely alliance with a group of outcasts, who help them navigate the political intrigues of Westeros.
A plot idea could involve the Direwolf OC being an outcast among its own kind. It then forms an alliance with a group of outcasts in Westeros, like a band of thieves or a small, forgotten clan. They all work together to change their fates. Another interesting plot would be if the Direwolf has the ability to communicate with other animals. It uses this power to gather information for its human companion, and they use this knowledge to outwit their enemies in the game of thrones. You could also have a plot where the Direwolf OC is the last of its kind and it's on a mission to find a way to repopulate its species.