Perhaps a plot where Remus helps Harry with his Patronus charm much earlier. Since Lupin is an expert in Defense Against the Dark Arts, he could teach Harry advanced techniques. Harry might develop a stronger and more unique Patronus, like a wolf, influenced by Lupin. This could change the way he faces Dementors in his early years at Hogwarts.
A really cool plotline could be that Remus, being a Marauder, tells Harry all about his father and the other Marauders in great detail. Harry gets to know the real James Potter, not just the heroic version everyone else tells him about. He also learns the true story behind the Marauder's Map and how it was created, which gives him a deeper connection to his father's legacy.
Perhaps a fanfiction could focus on Remus Lupin's past at Hogwarts before Harry arrived. Then, as the story progresses, it shows how his past experiences shape his interactions with Harry, especially in dealing with the challenges that Harry faces during his time at Hogwarts.
One interesting story could be where Remus Lupin helps Harry Potter train in advanced magic during the summer holidays. This gives Harry an edge in his fight against Voldemort.
The relationships he has with other characters are also fascinating in fanfics. His friendship with Sirius Black, for instance, can be explored more deeply. Some fanfics might show their time at Hogwarts together, their pranks, and how they supported each other through difficult times.
He might be more reserved and empathetic. Remus is a rather quiet and introspective character, and Harry would likely pick up on those traits. He'd be more understanding of those with differences, like werewolves, given Lupin's condition.
One great fem Harry Potter and Remus Lupin fanfiction is 'A Different Path'. It explores an alternate universe where Harry is female and her relationship with Remus develops in a very interesting way. It delves deep into their characters and how they interact in a world full of magic and mystery.
A plotline could also be about her relationship with the Marauders. Since Remus is part of the group, she could have her own interactions with them. She might become friends with them, or there could be some initial tension. For instance, Sirius might be overprotective of Remus and be a bit wary of her at first, but then they grow to understand and trust each other over time.
Many 'Harry Potter Remus Lupin fanfiction' deal with his sense of isolation. Despite having friends, he often feels alone because of his condition. Writers explore how he overcomes this feeling or succumbs to it. His relationship with the wizarding community at large, whether they accept or reject him due to his lycanthropy, is also a common theme.
One idea is that a dark wizard targets Remus Lupin and Sirius Black because of their close relationship with Harry Potter. The fanfiction could focus on how they protect themselves and Harry, and how this situation brings out new aspects of their magical abilities and their bond with each other. They might have to seek help from some unexpected allies within the wizarding world to survive.
One possible plotline could be that the Potter elves teach Harry unique magic that is different from what he would learn at Hogwarts. For example, they might show him ancient elf magic that gives him an edge in dealing with dark forces. Another could be that the elves raise Harry with a strong sense of family and loyalty, which makes him more empathetic towards those who are often overlooked in the wizarding world, like house - elves themselves.
One possible plotline could be that Charlus Potter imparts unique magical knowledge to Harry. Since he's from an older generation, he might teach Harry some long - forgotten spells or magical traditions. Another could be that Harry grows up with a different social circle, perhaps more connected to the old pure - blood families through Charlus. And also, Charlus might train Harry in a more traditional and strict way of magic compared to what Harry would have experienced at Hogwarts with Dumbledore.