Well, Goku could enter the Game of Thrones world during one of his training sessions where he accidentally travels through dimensions. In this new world, he would find the concept of the Iron Throne and the power struggle very strange. But his nature would make him oppose tyrants like Joffrey. He might start his own 'Saiyan - style' kingdom where strength and honor are the main values. His interactions with characters like Tyrion would be interesting, as Tyrion is a smart strategist and could potentially learn from Goku's combat skills while Goku could learn about the complex politics from Tyrion.
Imagine Iron Man arriving in Westeros during the White Walker invasion. His repulsor rays and energy shields could be extremely effective against the undead. He could also use his technology to communicate over long distances and coordinate the defense of the Seven Kingdoms. His presence would surely disrupt the existing political and military order in the Game of Thrones world.
The merging could happen with a common enemy. Suppose there's an alien - like threat that starts to invade Westeros. Master Chief, being a hero used to fighting off extraterrestrial foes, steps in to help. His military tactics and combat skills would be a huge asset. He could train the soldiers in Westeros in new forms of warfare, and in the process, he'd have to navigate the complex political and cultural landscape of the Seven Kingdoms.
One way could be through magic. In the world of Harry Potter, Tom Riddle is a powerful wizard. In Game of Thrones, there is also magic, albeit different. Riddle could perhaps use his dark magic to cross over into the Game of Thrones universe. Maybe he'd be drawn to the power struggles there, similar to his quest for power in the wizarding world.
The merging could also happen due to a powerful artifact. Suppose there is an ancient artifact in Skyrim that has the power to connect different realms. If it gets activated, it could pull the world of Game of Thrones into Skyrim's universe. Then, the political intrigue of Game of Thrones, like the power struggles in King's Landing, could be introduced to Skyrim's cities. The Nords in Skyrim would have to deal with the complex politics of the Seven Kingdoms.
One way they could merge is through a magical portal. Imagine if the demigods from Percy Jackson's world accidentally stumble upon a portal that leads them to Westeros. They might bring their unique powers, like Percy's control over water, and it would disrupt the power balance in Game of Thrones. For example, they could help in battles against the White Walkers, using their god - given abilities. This would change the whole course of the Game of Thrones story.
One way they can merge is through character crossovers. For example, a character from Game of Thrones like Jon Snow could be transported into the Warhammer universe. He might find himself in the middle of a battle between different factions in Warhammer, using his skills learned in Westeros to survive. His sense of honor and leadership could also have an impact on the Warhammer characters he encounters.
A pregnancy for Sansa in relation to Jaime would completely shift their story arcs. For Jaime, it could be the ultimate test of his new - found moral compass. He has already broken away from some of his family's more cruel ways, and this would be another step in that journey. For Sansa, it would add another layer of vulnerability and strength. She has grown from a naive girl into a strong woman, and a pregnancy would force her to be even more resilient. It could also lead to some interesting interactions with other characters, like Tyrion who has his own complex relationship with both Jaime and Sansa.
One possibility could be the rebuilding of Westeros. After all the destruction and power struggles, the remaining kingdoms might focus on restoring their lands, economies, and populations. New leaders could emerge who are more interested in peace and cooperation rather than conquest.
One possible alternate storyline could be that Robert manages to uncover the truth about Cersei's infidelity earlier. This would lead to a major political upheaval in King's Landing. He might exile Cersei and her children, which would change the power dynamics completely. With no Lannister influence at court, Ned Stark might have more sway, and the events leading to the War of the Five Kings could be averted.
Well, perhaps the magic in 'Game of Thrones' could be related to the advanced technology of Atlantis. For instance, the wizards in Westeros might be seen as having a similar power source as the Atlantean crystals or something. It could make for a really cool story where the two worlds' power systems are intertwined.