There's a fanfic called 'Padfoot and Moony's Little Cub'. In this one, Sirius and Remus raise Harry in a cottage hidden from the wizarding world. Harry grows up learning about his parents from the two men who knew them best. It has some really heartwarming scenes where they celebrate Harry's birthdays and teach him about the Marauders' adventures.
I'm not sure of a specific titled fanfic, but a good fanfic in this concept would likely explore how Remus' academic knowledge and Sirius' practical magic experience combine to give Harry some extraordinary private lessons. It might include lessons on advanced defensive magic, or understanding the history of the wizarding world from a different perspective.
I really like 'A Ray of Hope in the Darkness'. In this fanfic, Sirius is depressed after the events that have befallen him. Remus is portrayed as a very patient and loving character. He slowly helps Sirius heal by being there for him, and the story is full of emotional moments that will make you feel for both characters.
There's 'Time Traveler Harry: Sirius' Salvation'. In this fanfic, Harry's time travel is a bit of an accident. But once he realizes he can save Sirius, he sets out on a dangerous journey. The story is full of action and adventure as Harry tries to outwit the dark forces that were after Sirius in the past.
One great fanfic could be 'The Marauders' Plan'. In this story, Remus and Sirius bring up Harry in a way that stays true to their characters. They teach him about magic, but also about friendship and loyalty, just like they had with their own group. Harry grows up with a deep understanding of his parents' world.
There are quite a few out there. You could try searching on platforms like Archive of Our Own. Just type in 'Sirius raises Hermione' in the search bar, and you'll likely find a variety of stories. Some might focus more on the magical training aspect, while others could be more about the emotional bond between them.
In some fanfics, they might find out through a letter or a message. For example, Dumbledore could leave a mysterious letter that reveals Harry's existence and his connection to them. It's a simple yet effective way to start the story.
Yes, there are such fanfics in the Harry Potter fandom. Some fans like to explore different relationship dynamics and create unique storylines where Sirius and Remus are Harry's fathers in a romantic relationship. These fanfics often play with the idea of an alternative family structure for Harry within the magical world.
Friendship is also a major theme. They share a unique friendship that is different from normal friendships. In these fanfics, it's often shown how they support each other through difficult times. For example, when Harry is facing problems at Hogwarts, Sirius and Remus are there to give him advice and stand by his side. And of course, the theme of magic and adventure is always present as they are part of the wizarding world and have to face various magical threats together.
One great 'Sirius helps Harry' fanfic is 'The Bond Beyond Blood'. In this fic, Sirius helps Harry master some advanced magic that Dumbledore didn't have time to teach him. It's really interesting as it shows a different side of their relationship, more like a father - son bond in the world of magic.
I really like 'The Moonlight and the Marauder'. It has a very interesting take on Remus and Sirius's relationship. It shows their friendship evolving into something more. There are some really emotional scenes that make you feel for the characters. It also has some cool plot twists that keep you hooked from start to finish.