One possible plot could be that Sherlock is investigating a series of murders that seem to be related to an ancient Assassin's Creed artifact. The assassins are also on the hunt for this artifact, thinking it holds great power or secrets. Sherlock's deductive skills and the assassins' combat and stealth abilities would clash and cooperate as they both try to figure out who the real killer is and what the artifact does.
Obviously, Sherlock Holmes would be one of the main characters. He would bring his brilliant mind and unique detective skills to the story. For the Assassin's Creed side, Ezio Auditore could be a great choice. His charm, combat skills, and experience in the assassin world would create an interesting dynamic with Sherlock.
Well, it allows for a lot of creativity. Writers can take the elements of Assassin's Creed such as the hidden blades, the Brotherhood, and the Templars, and mix them with Holmes' character. They can create new storylines where Holmes might befriend an Assassin or go against the Templars. Also, the different time periods and settings in Assassin's Creed provide a great backdrop for Holmes' adventures. He could be in medieval Jerusalem or Renaissance Italy, adding a new dimension to his character.
One possible interesting plot could be an Assassin in Middle - earth. The Assassin could use their skills to infiltrate Mordor and take out key Sauron's lieutenants. They might team up with the Fellowship, sharing their stealth and combat techniques to help in the fight against the Dark Lord. For example, the Assassin could use their parkour skills to navigate the treacherous mountains around Mordor, getting to places that are hard for others to reach.
Well, one possible plot could be that an Assassin from the Assassin's Creed universe somehow gets transported to the world of Strike Witches. He could find himself in the middle of the battle against the Neuroi. Using his assassin skills like stealth and parkour, he could start to help the Witches in unexpected ways. Maybe he teaches them some new combat techniques based on his own training, and in return, the Witches introduce him to their unique magic - powered flight abilities.
One possible plot could be that a pony discovers an ancient artifact in Equestria that has Assassin's Creed - like powers. Maybe it gives the pony the ability to blend into the shadows like an assassin and jump incredibly high. The pony then has to use these new powers to protect Equestria from an unknown threat that is slowly emerging and wants to take over the magical land.
A cool plot could be that the Templars in the Assassin's Creed world somehow get hold of some ninjutsu scrolls. They start using these to create an army of super - soldiers. The Naruto characters then team up with the assassins to stop the Templars. Naruto could use his Rasengan against the Templars' new warriors, while Altair could use his eagle vision to spot their weaknesses. Together, they could form a unique combat strategy that combines the best of both worlds.
You could write a fanfic about how the Syndicate interacts with other Assassin's Creed groups around the world. The Frye twins might receive a message from an Assassin cell in another country asking for help. This could involve traveling to a new location, facing new enemies, and learning about different Assassin traditions. It would expand the world of Assassin's Creed Syndicate and show how the fight against the Templars is a global one.
One idea could be that Naruto, with his ninja skills, gets transported to the Assassin's Creed world. He might mistake the Assassins for a new type of ninja. He could then start learning their ways, like using the hidden blade in combination with his own jutsu. Another plot could involve Naruto teaming up with an Assassin to take down a powerful enemy that is causing chaos in both the Naruto universe and the Assassin's Creed universe.
A really interesting plot would be if the Akatsuki from Naruto were somehow related to the Templars in Assassin's Creed. Maybe they share a common goal, or there's a power struggle between them. Or, imagine a scenario where Sasuke becomes an assassin. He already has the skills and the brooding personality. He could use his Sharingan to enhance his assassin abilities, like predicting enemy moves better.
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.