According to J. K. Rowling, Ron was among the characters she created "the very first day".Ron is inspired in Rowling's best friend Sean Harris (to whom Harry Potter and the Chamber of Secrets is dedicated), but she has clearly stated that she "never set out to describe Sean in Ron, but Ron has a Sean-ish turn of phrase." Ron is "always there" when Harry needs him. The character of Ron fits many of the stereotypes expected of the sidekick; he's a comical character often called upon to lighten the mood, is loyal to the hero, and lacks much of the talent Harry possesses, at least in terms of magical power. Unlike some sidekicks, he is not cowardly, demonstrating bravery several times, such as entering into the Forbidden Forest with Harry in the second book, despite his phobia of spiders. Ron usually receives little recognition, whilst Harry's fame usually puts him at the centre of attention instead. This sometimes creates a rift between the two friends. Also, Ron comes from a large family, which hampers his resources. Most of his clothes are hand-me-downs, and when he damages his wand, he is unable to afford its immediate replacement. This in itself creates comical and unexpected results.Rowling introduces Ron as "tall, thin and gangling, with freckles, big hands and feet, and a long nose.Rowling in an interview described Ron as very funny but insensitive and immature, "There’s a lot of immaturity about Ron, and that’s where a lot of the humor comes from." Commenting on Ron's character development in the final book, Rowling explained that "Ron is the most immature of the three main characters, but in part seven he grows up. He was never strong footed, people see him mostly as Harry's friend; his mother had actually wanted a girl and in the last book he finally has to acknowledge his weaknesses. But it's exactly that which makes Ron a man."

He is a good chess player and has considerable wit; however, is a fairly average student, and is often too lazy to bother with his studies, a habit enabled by Hermione's perfectionist need to do even other people's work for them. With Harry and Hermione, Ron tends to use his sarcasm to bring his friends back to reality when they are formulating far-fetched concepts. There is a highly ambitious side to Ron, and he wants dearly to be popular and successful, due mainly to feelings of being overshadowed by his older brothers and best friend. Despite great loyalty to his family, he occasionally shows signs of being ashamed of their economic situation. This has occasionally manifested itself into fights with Harry out of jealousy. Like many of the boisterous Weasley family, Ron has a tendency to argue. This trait is never so present as it is in his relationship with Hermione Granger where bickering is a staple of their relationship, and is often how they best communicate. He seems to show surprise when some, such as Harry, express annoyance at their arguing, as neither he nor Hermione appear to think it is a big deal. In their arguments, while Hermione's tone tends to be patronising, Ron is more often than not bitingly sarcastic.