Well, one of the most popular characters in Naruto Shadow Blade fanfiction is Gaara. His control over sand and his past experiences make him a fascinating character to pair with the shadow blade. He could use the blade to enhance his already powerful abilities. Another popular one is Shikamaru. His intelligence and his shadow - based jutsu could be related to the shadow blade in various ways. And then there's Neji. His Byakugan and his family's history can be used to create engaging stories when combined with the mystery of the shadow blade.
In Naruto Shadow Blade fanfiction, characters like Itachi are quite popular. His calm and powerful demeanor, along with his Mangekyou Sharingan, can be incorporated into stories involving the shadow blade in interesting ways. Hinata can also be a popular character in these fanfictions. Her gentle yet strong - willed nature can be used to contrast with the dark and powerful nature of the shadow blade. And of course, Rock Lee. His unique fighting style without using ninjutsu can be combined with the shadow blade in creative fanfiction plots.
Naruto himself is often a popular character in such fanfiction. Since he's the main character of the original series, fans like to write about him interacting with the shadow blade. Sasuke is also popular as he has a natural affinity for powerful weapons and his dark - themed abilities could be linked well with the shadow blade. Another popular character could be Kakashi. His Sharingan and combat skills make him an interesting candidate to be associated with the shadow blade.