Larry is a bodybuilder and is often seen competing or working out with other sea creatures. He is always seen in his swim trunks, even when he is not at the beach, similar to Patrick. He regularly goes to Bikini Bottom's beach, Goo Lagoon, and works as a lifeguard there, as seen most notably in "SpongeGuard on Duty." Larry is one of the strongest creatures in Bikini Bottom, possibly second only to Sandy Cheeks, of whom he is a good friend of. Larry is very popular and is idolized by many other beachgoers. In "Band Geeks," it is stated that Larry's heart once gave out from too many tanning pills, and in "Roller Cowards" he is revealed to have a bad armpit odor that is caused by adrenaline. Larry has also run for Bikini Bottom president against Patrick Star. His campaign slogan is "Do you want a president that does not drool when he thinks? Vote for Larry!" Despite this, he lost to Patrick by about 90% of the votes. Larry's implied parents appear in "SpongeGuard on Duty." However, they are not lobsters; they are generic "old person" character models (it is likely that he was adopted). Larry kicks his own parents off of the beach for being too "old and unsightly," in an ironically polite manner.
He is a popular individual and is considered an "awesome" lobster by everyone; he also takes pride in being a lifeguard, knowing that he is the only thing separating the Bottomites from a watery grave. He has been seen to be furious in "Bubble Buddy" and "A Life in a Day," for a good reason. He has even kicked out his own parents for being old, but so politely they did not take offense to it. Despite his muscular physique, he is somewhat cowardly as shown in "A Life in a Day."
While Larry is strong, polite, and friends with SpongeBob, he is sometimes full of himself. This is seen when he completely ignores the Flying Dutchman, instead ranting about his body. There is also a part of the song "Ripped Pants" where the lyrics are "when big Larry came 'round just to put him down." Earlier in the episode, he also acknowledges SpongeBob as something of an underling, similar to Squidward. However, Larry has grown into a good friend of SpongeBob despite this.
He can also be very extreme in sports occasionally, and when Patrick and SpongeBob land in Rippers' Reef, Larry gets very angry at SpongeBob because the three of them are injured.
Larry's first real interaction with SpongeBob is in "SpongeGuard on Duty," and he is pretty impressed when he sees the drop of ice cream on his nose, thinking it is sun tan lotion, or as it is referred to as, "white stuff." Larry seems to interact well with SpongeBob, talking to him when he's around and creating small talk with him quite often, as he asks him to help him spread sun tan lotion on himself in "The Abrasive Side," and compliments him in "Pets or Pests."
In "Pet or Pests," when SpongeBob asks Larry about his worm pets, Larry asks, "Do I... know you?" SpongeBob replies, "Probably not." This shows that, although they have interacted, they do not really remember each other well, although Larry could be saying that because he felt embarrassed being near SpongeBob.
In the episode "Larry's Gym," Larry attempts to build SpongeBob in his own image, and succeeds. Later, all of the paperwork causes Larry to neglect his body, and his muscles deteriorate. SpongeBob becomes Larry's personal trainer and helps him get his old body back. After working out, the two share a hug.
Patrick's opinions about Larry have changed drastically throughout the show, going from disliking him to idolizing him, and eventually seemingly being acquaintances with him. In "SpongeGuard on Duty," it is implied that Patrick does not like Larry much, as he criticizes him for being overrated, stating that all he does is blow on his whistle, rub white stuff on his nose, and show off his body.
In "A Life in a Day," Patrick looks up to Larry as a role model, and begins trying to live like him. Eventually he loses enthusiasm for this, but SpongeBob pressures Patrick into taking part in one last dangerous stunt, during which Larry tries (and fails) to save them.
In "You Don't Know Sponge," after upsetting SpongeBob by failing to recall anything about him, Patrick meets with Larry to go shopping for a gift for SpongeBob, which initially confuses SpongeBob, as he believes Patrick has already moved on from their friendship.
Larry gets along pretty well with Sandy, since they are both into sports and both are very athletic. In "Ripped Pants," he invites Sandy and SpongeBob for weight lifting, and they both impress each other with their skills. Also, in "MuscleBob Buffpants," he and Sandy both participate in the Anchor Toss.
Larry and Squidward haven't really been seen together much but in "Squid Plus One," they are friends until Squidward starts mocking him about protein shakes. Larry promptly beats Squidward to a pulp.
Larry's first encounter with Mr. Krabs is in the episode "Larry's Gym." When Mr. Krabs hears that the first visit at his new gym is free, he vows to stay there forever. After Larry starts to lose shape, Mr. Krabs starts to tease him. Larry falls into a deep depression until the end of the episode, when SpongeBob helps him get back into shape. Mr. Krabs is cooked alive after spending too much time in the tanning salon short after.
In "The Check-Up", Larry agrees to pose as Mr. Krabs in order to help the latter pass his physical.
In "Larry the Floor Manager", Mr. Krabs takes a vacation and makes Larry the Lobster the temporary manager of the Krusty Krab.
"Anybody up for some volleyball?"
"SpongeGuard on Duty"
"You know, SpongeBob, the babes in the big chair are great, but the best part is knowing that you're the only one standing between these good people and a watery grave. That's what it's all about. Their lives are in your hands now, 'cause I have a date with the tanning booth. So long."