A Servant could be a famous inventor from history, like Nikola Tesla. His abilities could be related to electricity and innovation. He could create powerful electric fields or develop new weapons on the spot using his knowledge. Another unique Servant could be a mythical sea creature, like a Kraken. It could have the power to control water and summon other sea monsters to do its bidding.
A great plot idea could be a twist on the class system. What if there was a 'Hidden Class' that was only revealed during this special Holy Grail War? This could lead to all sorts of new strategies and power dynamics. Also, making the Grail itself have a different purpose or a hidden agenda. Instead of just granting wishes, it could be a key to something much larger, like unlocking a lost realm of magic.
One interesting concept could be new Servant classes. Maybe there are unique combinations of skills and abilities that are different from the original classes in the regular Fate series. For example, a Servant with a blend of Assassin and Caster abilities, which would make for very stealthy and magically powerful combat strategies.
One could be a young female mage as the main character. She might be from a family that has been on the outskirts of the mage society and is trying to prove herself in the Grail War.
Perhaps the story focuses on a previously unknown Master. This Master could be a young mage who accidentally stumbles upon the Grail War and has to quickly learn the ropes. They might form an unexpected bond with their Servant, like a Servant who is usually seen as cold-hearted but warms up to this inexperienced Master. This new dynamic could lead to a whole new set of adventures and challenges in the Grail War.
Another plot idea might be to have a twist where the Grail itself has been corrupted in a different way than in the original story. Maybe it's being influenced by an external dark force, causing the heroic spirits to act more erratically and forcing the masters to question the true purpose of the Grail War.
Perhaps a character who is not a traditional mage but a normal human who has somehow been thrust into the Holy Grail War. This person could have an innate ability to nullify magic, which would make them a very interesting wildcard in the war. They might be able to form an alliance with a Servant who has a grudge against the magical system and together they could try to change the rules of the Holy Grail War.
A character from a non - mainstream mythology, like a deity from Inuit mythology. This would bring in a whole new set of powers and cultural elements. For example, a spirit with the ability to control ice and snow in ways that are unique to Inuit beliefs.
Archer is often very popular. His cool and somewhat aloof personality, along with his powerful abilities, make him a favorite. Saber is also a top pick. Her noble image and strong sense of justice are appealing. And Gilgamesh, with his over - the - top arrogance and incredible power, is frequently featured in fanfiction.
One interesting concept is alternative Servant summonings. For example, seeing a different class for a well - known character like if King Arthur was summoned as a Caster instead of a Saber. Another concept could be different Masters, perhaps a non - traditional or more morally ambiguous Master. And then there are the alternate storylines that might change the location or rules of the Holy Grail War.