One thing that makes the Harry Potter series so endearing to fans is the sheer amount of characters that get introduced throughout the series, as even the most minor side characters often have their own fanbase. Harry Potter fans love to extrapolate and take a character that has very little written about them and write their own complicated backstory to their life. Of course, there are also characters who have actual canon backstories and roles in the narrative, despite the fact that they're not one of the main characters.