In the Spongebob universe, Squidward was raised by Jeff and Mrs. Tentacles and soon moved in with Spongebob and Patrick years later. The YTP universe Squidward was born to Davy Jones and Calypso, who threw him into the sea because he was too ugly. Squidward then grew up in a colony of squids in the then beautiful Bikini Bottom. Squidward was married to his clarinet until his affair with Ika Musume.
In his original universe, Squidward works as a cashier at the Krusty Krab working under the supervision of Mr. Krabs and with Spongebob acting as a frycook. In the YTP universe, however, Squidward "works" primarily at the Krusty Krab where he routinely falls asleep, reads books, and takes as many bathroom breaks as he can all in the middle of his shift. It can easily be said that he is not one of the better employees; then again, only two people have worked there.
Squidward is a dealer of guns, explosives, and other legally inaccessible weapons. He has ties with several terrorist organizations and hostile immigrants who buy his overpriced weaponry. Most of his wares are stolen from military arms shipments.
On the side, Squidward secretly grows marijuana that he sells behind the Krusty Krab. Being the only citizen in Bikini Bottom who has not used it to the point of brain damage is why Squidward considers himself the smartest in town.
The Rise of Squegee
Squidward's rivalry against Weegee first began after Squidward accidentally demolished the Weegee Towers, a hotel that Weegee was using to lure in unsuspecting tourists. After the accident, Weegee relentlessly stalked Squidward, planning an act of revenge until he decided on attacking Squidward in his own bathroom. Weegee attempted to turn Squidward into another Weegee clone, but Squidward was so shocked that the Weegee Virus was distorted and Squidward became Squegee, a cephalopod Weegee monster that was even stronger than Weegee! Squeegee even had a more dangerous Weegee Stare that killed victims directly instead of turning them into Weegees. This new stare came to be known as the Fad Stare of Explosion.
Weegee didn't even stand a chance until all the Weegees joined forces to fight Squeegee. But even then, Squeegee evolved and developed leveled-up forms (including Fire, Dark, Metal, and Super) that, after being experimented on by Plankton, became separate organisms, and also managed to hire mercenaries to hunt and kill Weegees. Said alternate forms could also merge to form one hyper powered Squeegee with infinite strength and abilities that could only be combated with Weegee and Malleo's combined form, Malweegee. The war extended as long as five years, but the Weegees finally beat Squeegee and reverted him back to Squidward. Then, just to rub it in his face, Weegee proceeded to throw toilet paper at Squidward's house. This turned out to be a huge mistake, as Squidward became angry and transformed back into Squeegee again (just like Jeckle and Hyde!). He then evolved, even MORE, alternate forms (like Ice, Thunder, and Final) and continued the Weegee-Squeegee Wars for another grueling year.
Sqeegee's theme: https://m.youtube.com/watch?v=UgGMkfK7FiA
Weegee's Death and Birth of The Skodwarde Squad
Seeing that the continuing war was greatly affecting his profits, Squidward anonymously tipped off and hired many bounty hunters such as Fionna to clip his enemy. They all either died or quit the job after encountering the monster, leaving Squidward no choice but to deal with Weegee himself.
In his basement, with the help of a hired group of scientists, Squidward created a militia of bioweapons in the likeness of him and his co-workers, the leader named Skodwarde. These artificial life forms had no conscience and knew no fear, remorse, or pity; the perfect assassins.
Squidward soon lost control of his bio army when they escaped his Easter Island home and into the streets. As a result of this and nightmares of Da-Da, Squidward's organization collapsed. He was then once again stuck as a disgruntled cashier at the Krusty Krab.
Although the YTP version of Squidward is classified as evil, there are multiple instances of Squidward acting as an protagonist or nonviolent side character. These include YouTube Poop: Skellington's Revenge, YouTube Poop: The Sky Had A Weegee!, and Squidward Gets Possessed by a Bad Lemon.