Well, modern technology in a Game of Thrones fanfiction would completely disrupt the power dynamics. Consider the Internet. If Westeros had the Internet, knowledge would spread like wildfire. People would be able to learn about different cultures and ideologies quickly. This could lead to the rise of new political movements. In terms of warfare, drones could be used for surveillance or even as weapons. It would be a strange sight to see a Lannister army being monitored by a drone from afar. And imagine the shock on people's faces when they first see a tank roll into King's Landing.
One way is through communication. For example, instead of ravens, they could use some sort of magical - technological device that can send messages instantly. This would change the way alliances are formed and wars are planned. Another aspect could be in the area of weaponry. Maybe there could be some advanced crossbows or swords with built - in tech that gives an edge in battle. Also, in terms of transportation, rather than horses all the time, there could be some sort of steam - powered or magic - tech vehicles.
A great plot twist in such fanfiction could be that there is a hidden underground society in Westeros that has been secretly developing modern technology all along. When they finally reveal themselves, they use things like laser weapons to take over King's Landing. Also, what if Bran Stark's warging ability could be enhanced by a neural - link technology? He could control multiple animals or even people at the same time, which would give him an incredible amount of power and change the balance of power in the story.
I think the Internet would be really interesting. It would completely change the way information spreads in Westeros. People could communicate across great distances instantly. Nobles could use it for political propaganda, and commoners could use it to organize against unfair rulers. It would also change the way knowledge is shared, like maesters could access a world of information instead of just what's in their libraries.
Modern tech would have a huge impact. Consider communication technology like the internet or mobile phones. Information could spread across Westeros instantly. This would prevent the kind of misinformation that often fuels the power struggles. For instance, Ned Stark might not have been wrongly accused if the truth could have been quickly spread. Also, in terms of transportation, airplanes or fast cars would make travel much quicker. Daenerys could have reached Westeros much faster to claim her throne, and perhaps prevent some of the chaos that ensued during her long journey with her dragons and ships.
In fanfic, advancing technology can change the power dynamics. For example, if the Starks got advanced weaponry like guns, they could better defend against the Lannisters. It might also change the way warfare is conducted, making traditional knights on horseback less effective.
Well, if we consider modern tech in Westeros in a fanfic, guns would completely change the way battles are fought. Armies that get hold of gunpowder technology first would have a huge advantage. For example, the Lannisters with their wealth could potentially mass - produce guns and gain even more power. Also, communication technology like radios would make it easier for lords to control their lands and respond to threats quickly.
One example could be the development of flying machines. This would change the way battles are fought and how people travel across Westeros. Another could be the use of magic - infused technology, like a weapon that channels magic more effectively.
One popular one could be those that focus on alternate endings. For example, a fanfiction where Jon Snow actually becomes the king of all Seven Kingdoms and rules in a more democratic way, uniting the North and the South. Another type might be ones that explore different relationships, like a fanfic where Arya and Gendry end up ruling the Stormlands together.
One interesting plotline could be a modern-day retelling where the political intrigue of Westeros plays out in a corporate setting. Characters might battle for control of a powerful company instead of the Iron Throne. For example, Jon Snow could be a young, idealistic employee trying to expose the corrupt practices of his superiors, much like the power struggles in the original series.