He is a light green sea cucumber. On the top of his head is a set of pale yellow feeding tentacles that looks like a crown (but, as Kevin mentions in his debut episode, is not a crown). The tentacles have an orange outline. He wears blue glasses along with brown colored shorts and has pink lips.
He is sadistic, treacherous, and ruthless, as shown when he let SpongeBob try out for the Jellyspotters only to humiliate and belittle him. He also lacked consideration for SpongeBob when he did harsh things for him such as jumping off a building and hitting himself. Humiliating and belittling others seems to be a habit of his, as many of his biggest fans have ended up trapped in a crevasse at Jellyfish Fields because of him.
He is also ill-tempered, as shown when he was annoyed by SpongeBob completing all his given tests with ease. Kevin was also greatly frustrated when all of his plans ended up with him getting stung by jellyfish.
Kevin is also ungrateful, as while he acknowledged SpongeBob saving his group from danger and calling him impressive, he still wouldn’t let him join because he didn't catch a queen jellyfish (despite the fact that it was a trick). This was a mistake that led to his followers turning on him.
At some point, Kevin became the leader of the Jellyspotters, an expert jellyfish enthusiast club, because of the fashion. The Jellyspotters then once became so popular that Kevin himself was the mascot of his own brand of jellyfish sting ointment.
Having no experience with jellyfish, he was replaced by SpongeBob, who proved to have experience with jellyfish and also saved them from a king jellyfish.
However, SpongeBob quit the Jellyspotters, and this lead the fate of the club to be left unknown.
In this episode, he meets SpongeBob and is creeped out by his obsessive fan boy behavior. However, he is greatly surprised when the latter complies with his requests such as jumping off a building and hitting himself. Amused by his attitude, he invites SpongeBob to go jellyfishing with the Jellyspotters who he tells that he wants to embarrass with pranks. He tricks SpongeBob into thinking he can join their club if he passes certain tests, simply so that he could humiliate and belittle him.
However, all of Kevin's plans end up with him instead getting stung by jellyfish one too many times, causing his hatred for SpongeBob to grow. Finally he snaps and says SpongeBob is ready for the final test: use SpongeBob as live bait to catch a queen jellyfish. It is revealed the Jellyspotters were using a robot queen jellyfish. Kevin and his friends then taunt and make fun of SpongeBob by calling him a "loser," but when a king jellyfish appears, he falls in love with the robotic queen and attacks them, Kevin proves to be a coward and admits that he was only in the club for the fashion.
When SpongeBob manages to ward away the king, Kevin was ruined when the Jellyspotters ripped off his crown-like cranium and put it on SpongeBob. Although SpongeBob left the club, it's unlikely Kevin retained leadership of the club, as he lost the loyalty of his teammates.
He appears at the Hotel Halibut's 36th Annual Jelly-Fisher Convention, where fans can meet Kevin and get pictures with him. He later appears at the episode's end, where he runs out of the fumigated hotel.
"Will you cut that out?!"
"All right, SquarePants, it's your turn to get zapped! I mean, are you ready for your final test?"
"Why don't you go jump off a building?"
"You're too kind. Security!"
"Bamboo? I only use composite materials in my net handle."
"Did you think we would actually let you join the Jellyspotters?"
"Well, SquarePants - that was impressive, but you're still not in the club because you didn't catch a Queen Jellyfish."
"Punch yourself in the face."
"Doesn't that hurt you?"
"Hey, kid. how would you like to try out for the Jellyspotters?"
"Look, I won't let the guy join the club. I just want to see how many times he can get stung before he goes running home like a baby!"
"Jellyspotters allow jellyfish to eat jelly - off their face."
"Oh, don't worry. We can't do it without you!"
"Well, then you've probably never used a queen jellyfish call. Why don't you try it out?"
"I'll bet you have."
"That's right! You should have seen the look on your face when we zapped you!"
"You looked so dumb with your dorky jellyfish call!"
"Don't look at me... I was just in this for the fashion!"
" I think he's gone. One of you, go out and check."
"It's hopeless! We're trapped! We're trapped! Help me, mommy! Help me! I want my blankie! I want my blankie!"
He doesn't seem to care about the well being of his fans, as he didn't care about SpongeBob punching himself twice or falling off a building.
Along with other fans of Kevin, he neglected them as well.
Kevin's "hat" is actually his tentacles. This is why he was in such pain when the Jelly Spotters forcefully removed it.