The Ashen One would be really interesting. They are a resilient and battle - hardened character. In Game of Thrones, they would be like a mysterious force. Their combat skills and ability to face all kinds of terrifying enemies in Dark Souls would make them a formidable presence in the political and war - torn landscape of Westeros. They could potentially be a wild card in the power struggles between the houses.
I think Solaire of Astora would be a great crossover character. His positive and somewhat naive attitude would be a contrast to the often cynical world of Game of Thrones. He could inspire some of the characters with his unwavering faith. And his skills with a sword and shield would make him a valuable ally in the battles. Maybe he would try to find his own 'sun' in the world of Westeros, which could be a metaphor for something different there.
Arya Stark would be really interesting. She has the skills of a trained assassin. In the Fallout world, she could use her stealth and combat abilities to navigate the dangerous wastelands and take on raiders or other threats. Her ability to change her face could also come in handy for undercover operations or infiltrating enemy camps.
Guts would be a very interesting character to crossover. His tough - as - nails attitude and his massive sword would make him stand out in the world of GoT. He has a lot of combat experience and a dark past, which could make for some great interactions with the morally ambiguous characters in GoT.
Daenerys Targaryen and Rosalie Hale would be an exciting combination. Daenerys is a strong and powerful queen, and Rosalie is a fierce and beautiful vampire. Rosalie could teach Daenerys some of her vampire - like self - defense skills, and Daenerys could show Rosalie how to rule with more confidence and grace. They could also form an alliance based on their mutual desire for power and respect.
Black Widow. She's a master spy and assassin. In the world of Game of Thrones, she could easily blend in with the various spies and informants. She could play the game of thrones better than most of the characters there, using her charm and combat skills to manipulate the situation to her advantage. She might even be able to uncover some of the deepest secrets of the Seven Kingdoms.
Jon Snow would also be a great addition. His journey from being a bastard to a leader in Game of Thrones could be paralleled in the world of Frozen. He could learn from Elsa about controlling his powers (if we assume he has some new ice - related powers in this crossover) and in turn, teach the people of Arendelle about loyalty and sacrifice, which are values he has held dear in Westeros.
Arya Stark in a 'Naruto Game of Thrones crossover fanfiction' would be fascinating. If she were to learn some of Naruto's ninja skills, she would become an even deadlier assassin. And Naruto's influence might change her path a bit, making her less vengeful and more about bringing real change to Westeros.
I think Ruby and the Chosen Undead would be a great pairing. Ruby is young and full of energy and idealism, while the Chosen Undead has seen so much and is a battle - hardened veteran. Their interactions could be really interesting as Ruby learns about the harsh reality of the Dark Souls world from the Chosen Undead.
Corvo Attano would be a great choice. His stealth skills and combat abilities would make him a formidable force in Westeros. He could easily blend into the shadows of King's Landing or any other city in the Seven Kingdoms. His ability to take down multiple enemies silently would give him an edge in the often - violent and politically charged situations in 'Game of Thrones'.
Definitely Cortana and Tyrion Lannister. Cortana is highly intelligent and has access to a vast amount of knowledge. Tyrion is known for his wits. They could form an alliance where Cortana provides strategic advice based on her analysis, and Tyrion uses his political acumen to make things happen. Their conversations would be really fascinating as they come from such different worlds but are both very clever.
One interesting combination could be Cole from Infamous and Jon Snow. Cole has his powers and moral dilemmas, and Jon Snow is all about honor and leadership. Their meeting could lead to some great discussions about power and responsibility. Another would be Fetch from Infamous and Arya Stark. Fetch's edgy nature and Arya's vengeful streak could make for an exciting duo.