As you may have heard, JK Rowling wrote an 800-word short story as part of a charity project. The card with her handwritten story was auctioned off today for almost $50,000. While she has been adamant that it is NOT a prequel, it is a story featuring James and Sirius during the first wizarding war with Voldemort but likely after they finished at Hogwarts.
You can read the story online for free by going here then clicking 'Read our authors' and selecting Jo. If you have trouble reading her handwriting, try this link.