There might also be other Autobots such as Bumblebee. Bumblebee could be Harry's friend, always there to help him out in tight situations. Maybe there's a human - Autobot liaison character who helps Harry understand the Autobots better. And let's not forget, there could be some antagonists from either the wizarding world or the Decepticons' side who play important roles in driving the story forward.
Kakashi could be another important character. His intelligence and wide range of ninja techniques can bring a different aspect to the story. And for the Autobots, Ratchet is often used. His role as a medic can be interesting when combined with the ninja's healing techniques in Naruto.
Starscream could also be a main villain in this fanfic. He is always looking for a chance to gain power and prove himself. He might see the battle of Autobot City as an opportunity to take over the Decepticons or get some valuable Autobot technology for his own gain.
Well, one possible interesting plotline could be Harry teaming up with the Autobots to fight a common enemy. Maybe there's a powerful Decepticon that threatens both the wizarding world and the Autobots' home planet, and Harry's magic combined with the Autobots' technology is the key to victory.
Harry is the central figure. But there could also be other students who become aware of Harry's situation. For example, Hermione might be a key character. She could be researching ways to either help Harry or deal with the consequences of his transformation. And then there could be a new character, perhaps a magical cat - keeper in the Forbidden Forest who has some knowledge about cat - like magic and can offer assistance to Harry.
There might be a villain, perhaps a dark wizard who is jealous of Harry's unique druid abilities. This villain would constantly try to undermine Harry and his efforts to use his powers for good, creating a lot of conflict in the story.
Well, it's hard to say for sure without reading the whole fanfic. But Harry is the central figure. There could be some older, wiser magical beings that are crucial to the story. They could guide Harry in his new life as a lich or try to put an end to his existence. And then there could be some ordinary wizards and witches whose lives are affected by Harry's transformation, and they might also be considered main characters in terms of how they impact the overall plot.
Obviously, Harry Vernon is a main character. But often, there are other characters created specifically for the fanfic or borrowed from the original source material if it's related to a known franchise. For example, if it's in a magical - themed fanfic, there could be a wise old wizard who guides Harry Vernon on his journey. Or a young sidekick who accompanies him in his adventures.
In Harry Colin fanfic, Harry and Colin are central. Harry could be depicted as a hero - like figure, with his own set of goals and dreams. Colin, on the other hand, might be there to support Harry, but also has his own story arc. He might have his own secrets or skills that are revealed as the story progresses, and together they create an engaging narrative.
It's also possible that some existing characters from the original Harry Potter series play important roles. For instance, Hermione could be trying to stop Harry from going down this wrong path at first, but then realizes there are deeper reasons behind his actions and ends up helping him in some way.
Well, obviously Harry is one of the main characters. He is the paladin at the center of the story.