Obviously, his friends Ron and Hermione would be among the first to join. Neville could also be a key member, as he has shown great courage. Then there might be the members of Dumbledore's Army who are still at Hogwarts. The Weasley twins could also be part of it, using their unique magical inventions to give the army an edge in battle.
The army could consist of a diverse group. There would be the students from Hogwarts, of course. But also, some of the outcasts like the werewolves who want to fight for a better place in the wizarding world. Hagrid could bring in some of his friendly magical creatures, like the hippogriffs. And those who have escaped from Azkaban and are against the Death Eaters would also likely join Harry's cause.
In this fanfiction, Harry might start by gathering his most loyal friends like Ron and Hermione. They could then recruit other students who feel oppressed by the Death Eaters' regime at Hogwarts. Harry could use his knowledge of magic, especially defensive spells, to train the army. Maybe they'd also include some magical creatures, like the centaurs or the house - elves who are willing to fight for a better future at Hogwarts.
Well, Hermione is an obvious choice as she's not only smart but also very loyal to Harry. Ginny would be there for sure, given her love for Harry. Then there could be some less - known characters like Astoria Greengrass. She might be drawn to Harry's charisma. And don't forget about Nymphadora Tonks. Although she's older, in a fanfiction world, she could develop an unexpected attraction to Harry because of his brave and selfless nature.
Maybe a new character, a Muggle - born wizard who was shunned by both the Muggle and wizarding worlds. This character, out of bitterness, decides to combine Muggle technology and magic to create the droid army and rule over both worlds. He would see Harry Potter and his friends as the main obstacles to his grand plan.
Neville would likely be one of the first to join. He has always been brave and has a strong sense of justice. Luna Lovegood might also be part of it. Her unique perspective and knowledge of the wizarding world could be very useful. And then there are the Weasley twins. Their skills in magic and their ability to think outside the box would make them great assets.
In this fanfiction, Harry might also include some of the Hogwarts ghosts in his army. After all, they have a long - standing relationship with the school. Peeves, for example, could be a wild card in the army. He can cause chaos among the enemies. And some of the older students who have a strong sense of justice, like Cedric Diggory's friends, could also be part of it.
Well, he might start by using his charisma. Naruto has always been good at making friends. He could reach out to old allies from his village, like Shikamaru and Choji. Also, he might convince some of the outcast ninja who have been mistreated in other villages to join him. His reputation as a hero who saved the world would surely attract a lot of people.
Well, it could be about a new threat emerging in the wizarding world where a droid army is created by a dark wizard who has mastered both magic and Muggle technology. Harry and his friends have to figure out how to defeat this army using their own magic skills and knowledge of the wizarding world.
Well, it could be a group of ordinary Muggles who rise to be leaders in the Muggle Army. Maybe there's a tech - savvy Muggle named Tom who uses his knowledge of electronics to find ways to detect magic. He could be one of the main characters.
Obviously, Harry Potter is one of the main characters as the title implies. He would be leading the army. His friends like Ron and Hermione would most likely be involved too, providing support and their own unique skills.
He could have found a magical artifact. There are many artifacts in the Harry Potter world that have strange and powerful abilities. It could be that this artifact has the power to create clones. He figures out how to use it, perhaps with the help of Hermione who is good at researching such things. And then he starts creating his clone army.