Kevin is the local jock in Ed, Edd n Eddy. He is cynical, and cruel at times. Kevin has a garage full of jawbreakers because his father works at a Jawbreaker factory, and loves customizing his bike, skateboards, and snowboards. When not riding his trusty bike, he usually hangs out with Rolf and Nazz in the lane. He, like every boy in the show except for Jimmy and Rolf, has a crush on Nazz. Whenever he sees her he gets all googly eyed and will do anything for her. Kevin is a gym assistant and hall monitor at Peach Creek Jr. High and enjoys playing sports. He hates the Eds to the point of paranoia, but especially despises Eddy because many of Eddy's scams have gotten him injured. He tends to call the Eds "dorks" and has a habit of coming up with words merged with dork to suit the situation. In fact, in the episode "All Eds Are Off", where some of the kids had to give up something they like for a bet, Kevin had to give up calling the Eds "dorks", which he could not refrain from doing for very long.
Kevin is the typical, popular, athletic jock that all the kids aspire to be.
He is the typical "cool" person in the group, laid back and slightly aloof. Kevin is most popular for the many athletic achievements accomplished on his beloved bike (and the occasional skateboard trick), and also for his skill in sports. He is especially respected by the unathletic children, such as Jimmy. The motive behind his constant display of athletic prowess is that he is a tremendous show-off, even moreso than Eddy. Kevin thrives on the constant attention and admiration that he earns. He brags about his father's job at the Jawbreaker factory, thus earning the respect (coupled with envy in Eddy's case) of the other kids.
Kevin adores his bike a lot. It is his most prized possession, and he is most often seen riding it or making repairs to it. He is most dangerous when someone endangers it in any way. He may care just a little too much about it, as seen in Ed, Edd n Eddy's Big Picture Show, when he was more worried about the well being of his bike than the well being of Nazz.
Kevin is also very cynical and can be a bully - mostly to The Eds, but sometimes also to Jonny and Jimmy. Even Rolf has fallen victim to Kevin's mocking and sarcastic attitiude on occasion, even though Rolf is his good friend. One incident prompted Rolf to ask, "Why must you mock us at every turn?"
He despises The Eds to the point of distraction and even to the point of paranoia. He can be friendly to Double D and he tolerates Ed, but he holds nothing but contempt towards Eddy and his constant schemes and hunger for attention. Kevin is most happy when he has the opportunity to utterly humiliate Eddy, but when you look at the big picture, they are very similar – both have big egos, they are huge showoffs, and both feel the need to be in charge.
There are only two things that frighten Kevin – needles, and Eddy's Brother. Upon learning it is booster shot day at school, Kevin goes pale and faints, falling off his chair in the process. Relishing the incident, Eddy exploits Kevin's terror, chasing him around the school with a gargantuan "needle" made from a trash can, a golf club, and other items. This blows back in Eddy's face when Kevin realizes the needle is fake, curing him of his phobia. The Wrath of Kevin then rains down accordingly. It is unknown if his fear is cured permanently, or just for this one episode.
Kevin is also scared of Eddy's brother. It is unclear if Kevin ever met him; rumors about him are enough to scare Kevin. This phobia also seems to be cured at the end of "The Big Picture Show", when Kevin faces off with Eddy's brother after the older boy severely injures Eddy.
Another thing that makes Kevin uneasy is talking "One on one" with Nazz. From "Pop goes the Ed" where he melted at the sight of her in a bathing suit. To him nervous sweating in "Boys Will Be Eds". And even his awkwardness and unwillingness into dancing with her in "May I have this Ed?". To him ignoring the signs that Nazz likes him in "The Big Picture Show".
It's obvious that Kevin doesn't have the intestinal fortitude to openly acknowledge his phobias (thus risking his popularity in the process); it becomes apparent that in some way Kevin fears for his position as the popular kid.