I think 'Naruto: The Elemental Master' is a top - notch fanfic. Here, Naruto gains control over all the elements in a very unique way, which sets him apart from his canon self. The story has great pacing and the fight scenes are beautifully written. 'Naruto: Reborn as a Jinchuriki' is another good one. It gives Naruto a new perspective as he is reborn with the knowledge of his previous life. And 'The Legendary Naruto' is a fanfic that really amps up Naruto's badassery. It has him facing god - like enemies and coming out victorious through his sheer will and newfound powers.
One could be John McClane from 'Die Hard'. He's tough, resourceful and faces numerous dangerous situations alone. Another is Sherlock Holmes. His brilliant mind and fearless attitude in solving complex cases make him badass. And then there's Aragorn from 'The Lord of the Rings'. He's a fearless leader and a great warrior.
The story of the 300 Spartans at Thermopylae is very memorable. They knew they were facing a huge Persian army but didn't back down. They fought with such ferocity that they held the pass for days. Another memorable one is the story of the Tuskegee Airmen in World War II. These African - American pilots had to face discrimination at home but still fought bravely in the skies over Europe, shooting down numerous enemy planes and proving their worth as pilots.
One common theme is the idea of sacrifice. The badass warrior often has to sacrifice something for the person they love. For example, in 'Akame ga Kill!', Tatsumi sacrifices his own safety and well - being for Akame and their comrades. Another theme is growth. The love story often forces the warrior to grow as a person. In 'Rurouni Kenshin', Kenshin grows and changes because of his relationship with Kaoru. He becomes more open and less isolated.
A really beginner - friendly fanfic is 'Naruto and the Lost Puppy'. It has a simple plot about Naruto finding a lost puppy and going on a small adventure to return it. It's cute and shows Naruto's kind heart. 'Naruto's First Mission Mishap' is also a good choice. It's about Naruto's first real mission going wrong in a humorous way. And 'The New Ninja in Town' is a fanfic that introduces new characters along with Naruto in a way that's easy to understand for those new to 'Naruto' fanfics.
Batman himself is obviously one of the most popular characters. He is the central figure and the source of the 'badass' factor in the fanfic. The Joker is also very popular as he provides a great contrast to Batman with his chaos and madness. Harley Quinn is often included as well, with her complex relationship with the Joker and her own brand of insanity. Another popular character is Robin, who represents the sidekick and the future of Batman's legacy.
In 'A Song of Ice and Fire', Arya Stark is extremely memorable. She's a young girl who becomes a badass assassin. Her journey from a naive child to a skilled killer, learning the ways of the Faceless Men, is amazing. Another is Geralt from 'The Witcher' series. He's a monster hunter with his own code of ethics, and his battles against all kinds of terrifying creatures are badass. And in 'The Name of the Wind', Kvothe is unforgettable. His intelligence, his skills in magic and music, and his ability to get into and out of trouble are what make him such a great and badass character.
One great anime is 'Akame ga Kill!'. It features a group of badass warriors fighting against a corrupt empire. Tatsumi, one of the main characters, has a complex relationship with Akame, which includes elements of love. Their story is filled with action, sacrifice, and a touch of romance.
One of the most interesting characters could be a new character created specifically for the fanfiction with a unique bloodline ability, like the power to create illusions so real that they can physically harm opponents. Another interesting character could be an existing character from the Naruto series whose bloodline is explored in more depth, such as Rock Lee if he were to have a secret bloodline that enhances his taijutsu in unexpected ways. And there's also the possibility of a villainous character with a bloodline that gives them the ability to steal other people's chakra.