Here are some words from the author about this character:
Although I never meant him to be like Sean, once I got Ron onto the page he often behaved like my oldest friend, who is both very funny and deeply loyal.
Can be viewed on the website.
Ron has to deal with his jealousy. He's made friends with the most famous boy in the year and that's not easy.
I myself am like Ron because I too am afraid of spiders.
As much as Ron loves his father [a wizard who is unusually curious about the nonmagic world], that can also be an awkward thing for a child, to have a particularly unconventional parent. It's plausible that these three kids would get on so well together because they are all to some extent oddities in the world.
bravenet.com