I would recommend reading the books first. The official Harry Potter books are a masterpiece. They introduce you to the magical world of Hogwarts in a detailed and well - crafted way. You get to know the characters like Harry, Hermione, and Ron in their original forms. Fanfiction, while often interesting, can vary greatly in quality. After experiencing the books, you can then explore fanfiction to see how other fans have reimagined the world or created new stories within it.
Read the books. The Harry Potter books are a classic for a reason. They have a consistent narrative, a deep lore, and a great deal of emotional depth. Fanfiction can be fun, but it's not the same. Some fanfiction might not stay true to the spirit of the original work. The books are the foundation upon which the entire Harry Potter fandom is built. Without reading them, you'll miss out on a lot of the subtleties and the overall grandeur of the wizarding world of Hogwarts.
Both have their merits. The books are the original source, filled with J.K. Rowling's brilliant world - building, complex characters, and an engaging overarching plot. Reading the books gives you the pure, unadulterated Harry Potter experience. Fanfiction, on the other hand, offers a wide range of interpretations. It can explore different relationships, what - if scenarios, and niche aspects of the Hogwarts world that the books might not have delved into deeply. So, if you want the true essence, start with the books, but for some creative and diverse takes, fanfiction can be great too.