In the fanfiction, their relationship could be developed gradually. At first, they might be very cautious around each other, but as they face challenges together, they start to trust one another more. Harry could help Tom to face his inner demons, and Tom could help Harry to better understand the darker aspects of magic without being tempted by them. This mutual growth would be a great way to develop their characters in the context of the story.
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.
It could also develop through a series of challenges. Say there are magical trials within the locket's magic. Harry and the Tom - essence have to face these trials together. As they overcome each obstacle, they learn more about each other's strengths and weaknesses, and their relationship grows from mutual respect in the face of danger.
The relationship between them develops in stages. Initially, they could be curious about each other. Harry might be intrigued by Tom's intelligence and magical abilities, while Tom could be interested in Harry's popularity and the mystery surrounding his survival. As time passes, they could start to compete in a friendly way, trying to outdo each other in classes or magical duels. However, this competition could also lead to mutual respect. Eventually, they may face a big crisis together, like a threat to Hogwarts, which cements their bond and makes their relationship one of true friendship and trust.
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.
One unique way is through a shared secret. For example, Fem Harry discovers a hidden part of Hogwarts that is related to a powerful and ancient magic. Tom Riddle also stumbles upon this secret. Instead of fighting over it, they decide to explore it together. During this process, they rely on each other's skills and knowledge. This shared adventure builds a deep bond between them, and they start to see each other in a new light, far from their initial impressions.
One idea could be that they work together to solve a mystery in the wizarding world that neither could solve alone. Maybe it's about a series of strange disappearances in Hogwarts that are linked to an ancient curse.
Well, in some fanfictions, Tom Riddle could be developed as having a bit of a conscience from the start. Maybe the diary contains some part of his soul that wasn't fully corrupted yet. So instead of being purely evil, he has moments of hesitation or confusion about his actions.
I think Luna Lovegood would be an interesting character to include. Her unique perspective on magic and the world around her could add an element of mystery and wonder to the fanfiction. Also, Severus Snape. His complex past and relationship with both Harry and Tom (in a way, as Tom became Voldemort) could bring a lot of depth to the story. And Hagrid, who could provide a connection to the more gentle and nurturing side of the wizarding world, which might be important for Harry and Tom's relationship development.
Hermione could be a major character. She might use her intelligence to try and figure out where Tom has taken Harry. She could be researching old spells or looking through Tom's past hideouts to find clues.
For Harry, his sense of justice and determination can be explored further. He might struggle with his feelings towards Tom as it goes against what he has always known about Voldemort. Tom, on the other hand, his intelligence and ambition can be shown in a new light. Maybe he is conflicted between his dark desires and the positive influence Harry has on him.