A really interesting event in a James Potter birthday fanfic could be a wizarding photo exhibition. All the pictures from James' life at Hogwarts, his Quidditch matches, his pranks with the Marauders, etc., would be on display. His friends and family could walk through the exhibition and share stories related to each photo. There could also be a special section where people could write down their birthday wishes for James, and those wishes would magically float around the room like little fireflies.
One interesting fanfiction could be where James Potter's birthday is celebrated at Hogwarts in a grand way. All his friends, including Sirius, Remus, and Peter, plan a surprise party for him in the Gryffindor common room. They decorate it with floating candles and his favorite Quidditch team banners.
James Potter's birthday was always a grand affair at Hogwarts. His friends, Sirius, Remus and Peter, would plan elaborate surprises. One year, they enchanted the Gryffindor common room to look like a Quidditch pitch, his favorite place. There were floating Snitches and mini - Bludgers. The whole Gryffindor house joined in the celebration, singing wizarding songs and sharing butterbeer. James was over the moon, his hazel eyes shining with joy as he thanked his friends for such an amazing birthday.
One common theme is family. Since it's James Sirius Potter, his family like his parents and siblings often play a big role in the fanfictions. For example, his father might give him an old family heirloom on his birthday.
A great Harry Potter birthday wish in a fanfic could be 'May your days be filled with as much magic as Hogwarts itself, and may you discover new spells and wonders every year, just like Harry did.'
One great 'James Sirius Potter birthday' fanfiction is 'James's Special Day' which beautifully depicts his birthday at Hogwarts with his friends and family. It has a lot of heartwarming moments.
Perhaps James had some hidden magical ability that he was unaware of until that moment. It could be something that was passed down through his family but had never manifested before. This ability could have protected him from Voldemort's killing curse. Or, it's possible that there was a plot by some other characters to save James. There could have been a group of wizards or witches who had been secretly working to keep James alive because they knew his importance in the fight against Voldemort. They might have used some sort of time - turning magic or a protective charm that Voldemort couldn't break through.
One interesting fanfic could be those that explore James Potter's time at Hogwarts before Harry was born. It might show his adventures with his friends, like Sirius and Remus. Another could be a fanfic where James Potter somehow gets to interact with Harry in a time - traveling scenario, which would be really cool.
The setting of the wizarding world. A good fanfic will use the magic, the Hogwarts environment, and the wizarding society to enhance their relationship. For example, a scene where they study magic together or go on a magical adventure in the Forbidden Forest can add a lot of charm.
One interesting plot twist could be that their resurrection is part of a grand scheme by an ancient magic user who wants to use their combined power for some dark purpose. But James and Lily, being the good people they are, resist and try to turn the tables on the evil plotter.
One interesting birthday wish could be to receive a magical creature like a Hippogriff. In Harry Potter fanfiction, characters often have a deep longing for unique and dangerous magical creatures. Another wish might be to get a time - turner so they can relive certain moments or study more magic. And a third could be to be accepted into a secret and powerful magical society within Hogwarts, like the fabled Order of the Phoenix.