A possible plotline could be that Voldemort has a change of heart. Maybe he realizes that Harry has some power or knowledge that he needs, so he decides to carry Harry away to a secret location to extract that information from him.
One common theme is mentorship. Remus, being older and more experienced, often mentors Harry. Another theme is protection, as Remus steps in to protect Harry from various threats. Family - like relationships are also common, where Remus fills the void of a family member for Harry.
In a post - war fanfic, Harry could be living in a more integrated wizard - Muggle society. There are still remnants of dark forces, but now the wizarding world is more open to Muggle technology. Harry, being a symbol of protection, decides to carry a gun as an additional means of safeguarding the peace. He trains with Aurors and Muggles alike to master the use of the gun, and along the way, he faces challenges from traditional wizards who oppose this new direction.
I'm not sure if there is such a fanfic. Fanfics cover a wide range of themes and scenarios, but this particular one might be quite rare or even violate some of the general guidelines of the Harry Potter fanfic community. Many fanfic platforms have rules against inappropriate or non - canon - compliant content.
There probably is. Fanfic communities are full of unique and unexpected plot ideas. This kind of plot would completely turn the original story on its head. It might involve some sort of alternate reality where Harry and Voldemort have a common goal or where they are forced to work together due to some external threat. It could be a really interesting read for those who like exploring different interpretations of the Harry Potter universe.
At first, it would be extremely tense and full of suspicion. Harry would be very wary of Voldemort's motives for protecting him. Voldemort, on the other hand, might be impatient with Harry's lack of trust.
Perhaps Voldemort discovers that there is a greater threat out there. In the fanfic, it could be that another dark force is emerging, and Voldemort sees Harry as an ally of sorts against this new threat. So, he decides to protect Harry in order to deal with this common enemy.
Snape could also be a character in such a fanfic. His complex relationship with both Harry and Voldemort makes him an interesting addition. He might be in a difficult position, having to keep his cover as a double - agent while also trying to find a way to save Harry without revealing his true intentions to Voldemort.
At first, it would probably be very tense. Harry would be suspicious of Voldemort's motives, and Voldemort would be cautious of Harry's potential to rebel. But as time goes on, they might develop a strange sort of understanding. Harry could start to see Voldemort as more than just a pure evil figure, and Voldemort might start to view Harry as something more than an enemy.
I'm not sure about a specific 'Remus carries Harry fanfic' off - hand, but you can try searching on fanfiction websites like Archive of Our Own. There are likely many stories there that focus on this relationship. You can search using the tags'remus lupin' and 'harry potter' to narrow down the results.