Squidward is a mean, whiny, stick-in-the-mud squid who thinks he's better than everyone else. Just about everything annoys him. The Krusty Krab annoys him. The customers annoy him. Mr. Krabs annoys him. But most of all, SpongeBob annoys him, almost 24 hours a day.
Besides working side by side with SpongeBob at the Krusty Krab, Squidward is SpongeBob's next-door neighbor. If it weren't for the fact that SpongeBob is the only one who likes listening to his clarinet playing, Squidward would have nothing to do with him. SpongeBob, on the other hand, thinks the two of them are the lunch shift dream team.