Well, it could be about Harry Potter finding a way to enter Tom Riddle's world in the fanfiction. Maybe he's on a mission to change Tom's path to the dark side.
It could be Voldemort. Even if it's a fanfiction where Harry joins Tom, Voldemort's future self might still be a threat and oppose Harry's attempts to change Tom.
Perhaps Harry joins Tom's eventual lover in order to uncover some secrets that Tom has been hiding. They could start off as distrustful of each other but as they work together, they find common ground. The plot might involve them traveling to different magical places and facing various challenges together while trying to figure out Tom's true nature.
There could be other Hogwarts students like Hermione and Ron. Hermione might offer her intelligence and knowledge to help Harry and Tom's lover in their journey. Ron could be there for comic relief and also provide some muscle when needed. And of course, there might be some of Tom's followers or enemies that play important roles in the story.
The wizarding world would be in shock. Harry has always been seen as a symbol of hope and the one who could defeat Voldemort (Tom). People would feel betrayed, especially his friends like Hermione and Ron. The Ministry of Magic would likely see Harry as a new threat and start devising plans to stop him. There would be a lot of fear and uncertainty among the wizarding population.
If Harry Potter were to join the Marines, it would be a very interesting combination. He might struggle with the muggle technology at first, but his determination and courage would help him adapt quickly. His magical abilities could potentially give the Marines an edge in combat situations, like using magic to disarm enemies or create barriers. Also, his experience with teamwork from his time with Ron and Hermione could enhance the camaraderie within the Marine unit.
Harry might develop a stronger sense of justice due to his Gryffindor influence, while Tom could be more influenced by Slytherin's ambition. So Harry focuses on helping others, and Tom on achieving his own goals.
Tom, on the other hand, could start to see the value in friendship and loyalty through working with Harry. His character could soften a bit, realizing that there are other ways to gain power and respect than through fear and intimidation. For example, he could learn from Harry's ability to inspire people. They could also have a sort of mentor - mentee relationship in some aspects, with each teaching the other different spells or magical theories. This would make Tom a more complex and well - rounded character.
They could start by having small moments of understanding. For example, when one of them is in trouble, the other shows unexpected kindness. This could gradually build trust between them.
There's also 'Harry and Tom: The Forbidden Alliance'. It's a fanfiction that delves into a rather complex relationship between the two. They find themselves in a situation where they have to form an alliance against a common, dark enemy, and the story is filled with intense magical battles and emotional turmoil.