There are quite a few fanfictions on this topic. Some might be on smaller fanfiction platforms. You can start by searching on well - known fanfiction websites. Look for tags like 'sirius x narcissa' or 'sirius marries narcissa'. You might find some hidden gems that show different interpretations of their relationship, from a love - at - first - sight scenario to a more politically - motivated union.
I'm not sure of the exact name, but there are some fanfictions where Sirius marries Narcissa that focus on the political implications in the wizarding world. Their marriage could be a way to bridge the gap between the pure - blood families who were on different sides of the conflict. These fanfictions often create a whole new dynamic in the Harry Potter universe.
One common theme is the idea of redemption. Sirius, being a 'rebel' and Narcissa from a more traditional Slytherin family, their union can symbolize a chance for both to redeem themselves in the eyes of different wizarding factions. Another theme is family reconciliation. Their marriage can be a means to bring together the Black family, which was divided, and the Malfoy family.
I'm not sure of specific 'narcissa marries harry fanfiction' titles off the top of my head. But you can try searching on fanfiction websites like Archive of Our Own. There are likely many stories with this concept there.
Finding 'Petunia Marries Sirius' fanfiction can be a bit of a treasure hunt. One tip is to look for fanfiction that explores alternate universes or 'what - if' scenarios in the Harry Potter universe, as this type of plot often leads to unique pairings like Petunia and Sirius. You could also try searching for authors who are known for writing unconventional pairings in the Harry Potter fandom.
One interesting plotline could be Narcissa and Sirius having to team up against a common enemy in the wizarding world. Maybe there's a dark force threatening both the Black family's reputation and Sirius's fight for justice. They start off distrusting each other but gradually learn to work together.
One common theme is family conflict. Given that they come from the same family but have very different paths in life, fanfictions often explore how their family ties both bind and divide them. For example, the expectations of the Black family and how they each rebel against or conform to those in different ways.
One possible plotline could be that in a post - war world, Narcissa and Harry find themselves drawn to each other through mutual understanding. Maybe Harry sees a different side of Narcissa that was hidden during the war, and they start to build a relationship from there that leads to marriage.
One possible plot could be that in a world where the war ended differently. Harry, having seen Narcissa's true nature in saving him at the end, starts to interact with her more. They find common ground in their love for Draco and a desire to heal the wizarding world. Their relationship slowly blossoms from there, with Harry helping Narcissa come to terms with a new world order, and Narcissa teaching Harry more about the pure - blood traditions in a non - prejudicial way.
Some good Harry and Narcissa fanfictions include 'The Meeting'. In this story, a chance encounter between Harry and Narcissa sets off a chain of events that alters the wizarding world. 'Harry and Narcissa: The Unspoken Understanding' is also worth checking out. It shows how they gradually come to understand and trust each other despite their different backgrounds. Additionally, 'The New Alliance' is a fanfiction that presents a unique take on their relationship, with both of them having to overcome many obstacles to work together.
There's also 'The Unlikely Bond'. In this fanfic, Hermione stumbles upon Narcissa in a difficult situation and decides to help her. Their relationship evolves in a very interesting way, full of twists and turns. It's a great read for those interested in this pairing.
There's also a story where Narcissa teaches Hermione about the dark arts defenses from a Slytherin perspective. It delves into how Hermione, being a Gryffindor, has to adapt to Narcissa's different teaching style. It's a really cool exploration of the two characters and how they can learn from each other.