The storyline might involve Dark Naruto being a mystery to the Hogwarts students and teachers. At first, they might mistake his powers for some new and extremely dangerous form of dark magic. He could disrupt the balance in the wizarding world. For example, he might try to take control of the Forbidden Forest, using his ninja skills to outwit the magical creatures there. And his presence could force the wizarding community to re - evaluate their understanding of magic and threats.
In a Harry Potter fanfiction with Dark Naruto, he could also be a lone wolf. He doesn't really side with anyone but himself. He might be interested in the Philosopher's Stone or other powerful magical artifacts in the Harry Potter world. His dark nature would make him willing to do whatever it takes to get his hands on these items. This could lead to many conflicts with Harry Potter and his friends, who would see Naruto as a threat to the safety of their world.
He could be a new teacher at Hogwarts. Since he's immortal, he has a vast amount of knowledge and skills. He could teach a new subject that combines ninja techniques and magic. For example, he could teach students how to use their magic in a more physical and combat - oriented way, like ninjas do.
Well, one way the storyline could develop is that Naruto's immortality would give him an edge in the wizarding world. He could use his ninja skills along with newfound magic abilities. Maybe he'd be a bit of an outlier in Hogwarts, not fully understanding the magic system at first but quickly adapting due to his ninja training. His immortality might make some dark wizards target him, thinking he holds some sort of secret to eternal life. And he'd probably form unique friendships, like with Harry, Ron and Hermione, teaching them some ninja moves in return for magic lessons.
The storyline would likely be affected in a major way. Dark Naruto's abilities are quite different from what we see in RWBY. He could potentially teach the RWBY characters new combat techniques. For example, his use of shadow clones could be a game - changer in battles against large groups of Grimm. However, his dark nature might also cause some of the RWBY characters to question their own moral compasses. His presence could also lead to power struggles within the RWBY teams as they try to figure out how to deal with this new and powerful entity.
One way it could unfold is that Harry somehow gets transported to Middle - earth. He realizes the danger Sauron poses and decides to take action. He starts by using his magic to help the free peoples of Middle - earth, like the hobbits or the elves. He might try to learn more about Sauron's weaknesses. As the story progresses, he gets closer to a final showdown with Sauron, using all his learned magic and newfound allies to face the dark lord.
The presence of Dark Naruto in My Hero Academia fanfiction would change things quite a bit. His combat skills and his chakra - based powers would be very different from the quirks in MHA. This could lead to some interesting battles and power - up scenarios. For example, how would heroes like All Might or Deku react to someone with such different powers? Moreover, Dark Naruto's backstory of being an outcast in his own village could parallel some of the characters in MHA who also face discrimination. This could lead to some complex character interactions and story arcs.
The new Dark Lord in this fanfiction could be a former Hogwarts student who was bullied and turned to the dark arts for revenge. They could start gathering followers among those who feel disenfranchised in the wizarding world. Their goal might be to rewrite the laws of magic to suit their own dark desires. They would likely oppose Harry Potter and his friends, leading to epic battles and tense stand - offs.
Perhaps Harry gets a job as a magical tutor for some young wizards. The story could develop as he tries to teach them the things he's learned over the years. He'd face challenges like dealing with difficult students or trying to teach advanced magic to those who are not ready. His experiences at Hogwarts would come in handy, but he'd also have to learn new teaching methods.
The prophecy about Harry and Voldemort would take on a new meaning. If Merlin was in Harry, he might see the prophecy as just another part of the cycle of good vs. evil that he has already experienced in Camelot. He would approach the battle with Voldemort with a different strategy, perhaps using his knowledge of ancient magic to find a more permanent solution to the dark wizard threat.
There's a chance he'd be inspired. The stories of the Naruto characters' determination and growth in the fanfiction could stir something in him. He might think about his own journey as a wizard and how he can further develop his skills and character, taking cues from the Naruto characters' tenacity.
Well, in this fanfiction scenario, Lily raising Harry would mean he'd be protected in a different way. Instead of the Dursleys' neglect, he'd have a nurturing environment. Lily could teach him about his father in a more personal way. Maybe he'd grow up with a stronger sense of family and heritage. Also, he might not have the same sort of scar - or it could be a mark of a different kind of magic, since the circumstances of his survival would be different.