Kenickie is always seen throughout the movie sporting typical greaser attire: a black leather jacket with a white T-Birds logo on the back; dark-blue jeans; a bluish-white T-shirt; a golden necklace around his neck; and black engineer boots. He's also a chainsmoker.
His facial features consist of dark-blond hair styled in a pompadour, like Danny, a cigarette behind one ear; and pale blue eyes.
As a T-Bird, he usually eschews any "soft" emotions, like caring and kindness. He gave Danny Zuko a "What's going on here?" look when Danny exclaimed in shock when he was reunited with Sandy Olsen. When Sandy told Danny he was a fake and a phony and ran away, Kenickie made the odd comment: "I wonder if she carries silver bullets." That could have been a reference to Danny's rapid transformation from nice guy to werewolf.
He did have a deeper side, though. When he and Danny are right outside the Frosty Palace (an ice cream parlor), he seems to be annoyed at the Scorpions for driving into T-Birds territory, and their hangout of all places, but when he turns to Danny, who has a sad facial expression, he softens up asking calmly: "Hey Danny, what's up? You still thinking about that chick?"
At the Drive-in, he's told that Rizzo's knocked up, and he tells her: "I don't run away from my mistakes." He did care enough about Rizzo to take responsibility. When she told him: "It was somebody else's mistake." he tried to laugh it off, but it cut deeply, and he sighed sadly: "Thanks a lot, kid." and left. Just before the race at Thunder Road, he and Danny have a best friend talk. Kenickie tells Danny that, since he's always been there for him, he wants him to be there with him at the race, not racing with him, but there to back him up. Of course, knowing they're best friends for as long as they can remember, Danny says yes to this, and the two of them hug, much to the confusion and concern of Doody, Sonny, and Putzie. Kenickie accidentally bangs his head on the car door and has Danny drive the car instead, and Danny wins.
Kenickie Hey Rizzo, I hear you're knocked up.
Kenickie The problem's in your mouth.