Link from The Legend of Zelda would be a fascinating character to include. His use of various weapons like the sword and bow, along with his acrobatic skills, are somewhat similar to the assassins in Assassin's Creed Odyssey. It would be cool to see how he would interact with the Greek setting and the characters there. Also, Conan the Barbarian could be an interesting addition. His brute strength and no - nonsense attitude would contrast with the more stealth - based approach of the assassins, creating some interesting storylines.
A character like Kratos from God of War could be really interesting in an Assassin's Creed Odyssey crossover fanfic. Kratos has his own complex backstory and his combat skills are formidable. He could either be an ally or an antagonist to Kassandra or Alexios. His connection to the Greek mythology world would add depth to the story. And if we think outside the box, even a character like Sherlock Holmes could be included. His deductive skills could help solve some of the mysteries within the game's world.
I think Ezio Auditore would be a great addition. He's a beloved character from the Assassin's Creed series. His skills and charisma would make for an interesting interaction with Kassandra or Alexios. They could learn from each other's experiences and combat styles. Another interesting character could be Lara Croft. Her knowledge of archaeology and survival skills would blend well with the world of Assassin's Creed Odyssey. She could join forces with the assassin to explore ancient tombs and uncover hidden secrets.
One idea could be a crossover with the Witcher series. Kassandra or Alexios could meet Geralt in a world where the Isu technology has somehow intersected with the magic of the Witcher world. Maybe they team up to fight a common enemy that is using both magical and ancient technology to cause chaos. Another plot could involve a crossover with the Lord of the Rings universe. The hero from Assassin's Creed Odyssey could be transported to Middle - earth and get involved in the War of the Ring, using their combat skills and stealth abilities to help the Fellowship in unexpected ways.
Xenia's role in the Assassin's Creed Odyssey world is quite unique. A fanfic could play with the idea of her being a key figure in a larger conflict that the game doesn't fully explore. For instance, she could be the only one who knows the location of a powerful artifact that many factions are after, and she has to use all her wits and resources to keep it out of the wrong hands.
Harry Potter and Altair would be a great combination. Harry's sense of justice and Altair's Assassin skills would make for an exciting duo. They could learn from each other, with Altair teaching Harry about stealth and combat techniques from the Assassin's Creed world, and Harry showing Altair the power of magic.
I think Naruto would be the most interesting. His energetic and determined personality would make for great stories in the Assassin's Creed world. He'd be constantly trying to adapt and use his ninja skills in new ways. His ability to make friends and inspire others would also lead to some interesting interactions with the assassins.
I think Sasuke would be quite interesting. His dark past and thirst for power could be paralleled with some of the Assassin's Creed characters' motives. He could learn new ways to use his skills in the Assassin's Creed world and maybe even find a new purpose.
Another angle for a fanfic about Xenia could be her relationship with the protagonist. Perhaps they form an unlikely alliance based on mutual respect and a common goal. They could learn from each other's skills and experiences, and this could lead to a strong bond between them as they journey through the game's world together.
How about Frodo Baggins? He has the One Ring, which could be a target for the Templars. The Assassin could protect Frodo on his journey to Mordor. The Assassin's skills would be useful in dealing with the various threats along the way, like orcs and Nazgul.
A more character - driven plot could be about the relationship between Kassandra or Alexios and their family members. You could write a fanfic that delves deeper into their feelings towards their mother, father, or siblings. What if there was a secret that their family was hiding from them all along? This could add a whole new layer of drama and mystery to the story.
A great plot for an Assassin's Creed Odyssey fanfic could be centered around a love story. The main character could fall in love with an enemy, like a high - ranking Athenian while being a Spartan assassin. They would have to navigate their feelings while also being true to their respective causes. It would add a lot of drama and tension. Also, a plot about a hidden cult within the game's world that the main character discovers and has to take down. This cult could be involved in dark magic or ancient rituals that are threatening the stability of the Greek world in the game.
One possible plot could be that the protagonist from Assassin's Creed Odyssey somehow gets transported to the world of PJO. Maybe they end up in Camp Half - Blood and are mistaken for a demigod at first. They then have to use their assassin skills to survive the various challenges in this new world, like facing off against mythical creatures that are different from the ones in their own world.