One popular original character added is a dark healer. This character might seem helpful at first but is actually using Naruto and Sasuke's wounds, both physical and emotional, to further their own dark agenda. They might be able to heal their injuries in a way that also taints their spirits. Another is a shadowy assassin who is sent to either kill or turn them to the dark side. This assassin has unique abilities that test Naruto and Sasuke's limits. Also, there could be a powerful dark sorcerer who is interested in the power of the Sharingan and the Nine - Tails, and tries to use Naruto and Sasuke as pawns.
There are original characters who are members of a secret ninja clan. They cross paths with Jiraiya and Naruto during their adventures. These characters bring in new ninja techniques and a different culture within the ninja world. Also, there could be a young orphan that Jiraiya and Naruto take in. This character could represent a new generation that they are responsible for, and it adds a new dynamic to the story of Jiraiya raising Naruto.
Obviously Naruto and Sasuke themselves are very popular. Their relationship and how it changes through time travel is a major draw. But also, characters like Kakashi can be popular. If Naruto and Sasuke travel back, Kakashi's reaction and how he interacts with them knowing their future selves can be really interesting.
In Dark Naruto Mokuton fanfiction, one popular type of original character is the healer. Since Naruto's dark side and Mokuton powers could potentially cause harm to himself or others, a healer character is created to keep things in balance. They might have unique healing abilities that work specifically with chakra imbalances caused by the dark side and Mokuton. Also, there are often original antagonists who are specifically after Naruto's Mokuton power because of its rarity and strength when combined with his dark side.
Sakura is often quite popular. In college fanfiction, she might be a brilliant medical student, still having her feelings for Sasuke while also becoming good friends with Naruto. Her strong - willed nature and intelligence can add a lot to the story.
One popular original character could be a mysterious mentor figure who helps Naruto understand and control his dark avatar powers. Another might be a villain who is specifically created to oppose Naruto's dark side, adding more conflict to the story. There could also be a healer - type character who tries to bring back Naruto's original self.
One common type of original character is a rival. This rival could be another ninja who also wants to harness the power of the Kyuubi, either for good or bad reasons. They might challenge Naruto and his brother at every turn. Another could be a healer who is specifically attuned to the Kyuubi's chakra and can help Naruto when he has trouble controlling it. There could also be an old sage - like character who has been around since the time the Kyuubi was first sealed and has secrets to share.
Kakashi Hatake is a popular choice. He has a long history with both Naruto and Sasuke, having trained them. He could be included to offer guidance or add some comedic moments. For example, he could give them some tough training exercises that help them bond more. Another popular character is Sakura Haruno. She has her own complex relationship with both Naruto and Sasuke. Her presence can add some drama, like if she has to choose between helping Naruto or Sasuke in a difficult situation.
I think Kakashi could be really popular. Since he has a connection to both Sasuke and Naruto, his role in a time - travel story could be very interesting. He might be able to help them adjust to the past or use their knowledge to his advantage. Another popular character could be Itachi. His actions in the past are so crucial to the story, and in a time - travel scenario, he could interact with Sasuke in a whole new way.
Sakura is a very popular character to include. She has a long - standing relationship with both Naruto and Sasuke. Her medical ninjutsu skills can be very useful in various plot situations. Kakashi is also popular. His experience and unique jutsu can add depth to the story. Another popular character is Shikamaru. His intelligence can be a great asset in devising strategies against enemies.
Dark Naruto himself is often a very popular character in such fanfiction. His transformation into a darker version of himself brings a whole new level of complexity and power. Dark Kyuubi is also quite popular as it adds an element of danger and mystery. Additionally, characters like Sasuke might also be popular as he could potentially have an interesting dynamic with Dark Naruto, either as an ally or an enemy in the dark - themed story.