You can start by searching on popular fanfiction websites like Archive of Our Own (AO3). Just type 'James and Regulus' in the search bar and you'll get a list of relevant fanfictions. Another option is to check out some Harry Potter - themed fanfiction forums. People there often share and recommend good fanfictions about different characters, including James and Regulus.
There's a fanfic called 'Regulus' Redemption and James' Understanding'. In this story, Regulus is on a journey of self - discovery after leaving the Death Eaters, and James is there to support him in ways no one expected. It's really interesting to see how their relationship develops. And 'The Secret Meetings' is also good. It focuses on the clandestine encounters between them and how their feelings for each other start to grow.
Harry is the central figure. However, Bellatrix Lestrange could be an important character in a different sense. As a Black, she might have some connection to Regulus and thus to Harry. And then there's Hermione. As Harry's friend, she would be there to support him through the revelations about his parentage. Her intelligence and loyalty would be key elements in helping Harry deal with the situation.
Some good James and Regulus fanfictions include 'A New Path for Regulus with James'. This one shows how James helps Regulus break free from his family's dark expectations. 'The Bond that Defies House Divisions' is also popular, which focuses on how their friendship overcomes the Gryffindor - Slytherin divide. And 'James and Regulus: In the Shadows' where they operate in the shadows to protect the wizarding world from a hidden threat.
One possible reaction of Sirius could be shock. He might stand there frozen for a moment, unable to believe what he's seeing. Another reaction could be anger. If Sirius has certain expectations or feelings about James and Regulus' relationship, he could get angry at finding them together. Or he could be confused, trying to figure out how and why this is happening between his friend James and his brother Regulus.
Friendship is also a big theme. Since they are from different houses in Hogwarts, exploring how they could have become friends despite the house rivalries is interesting. Some fanfics might show them bonding over shared interests or a common goal, like fighting against the Dark Arts in a more united way than in the original story.
You can start by searching on popular fanfiction platforms like fanfiction.net and Archive of Our Own. Just type in'regulus x james' in the search bar and a whole list of relevant fanfictions will pop up. You can also join fanfiction - related groups on social media platforms like Facebook or Reddit. Members often share their favorite stories or recommend new ones.
A plotline could involve Harry's discovery of his true parentage. Maybe he grows up thinking he's just James' son, and then finds out about Regulus. This could lead to a journey of self - discovery, as he tries to understand the parts of himself that come from both his fathers. He might also face opposition from some in the wizarding world who can't accept this unusual family situation.
Another theme is self - discovery. Through their relationship, both James and Regulus learn more about themselves. They might discover new aspects of their personalities or hidden desires. In some fanfics, this is shown as they face difficult situations together and have to reevaluate who they are.
This event could severely strain Sirius' relationship with James. If Sirius feels that James has overstepped some sort of boundary regarding Regulus, he may become distant from James. With Regulus, it could be a turning point. Sirius might start to see him in a new light, either more positively if he realizes that James is a good influence, or more negatively if he doesn't like what he sees.