Fagin first appeared in Spongebob and friends in cat's don't dance as he was feasting on sadness and depression from his broken hearted victims, even that of Sawyer. The dark reason why he was doing so was for his personal entertainment. But thanks to the spunkiness of Danny, and the shell louge squad, he was defeated and banished from hollywood (the Hyenas gaved him the birdy boiler treatment).
It may be possable that he'll return again to wreak his horrable vengeance. (He did appear again, but it was a cameo in Kids World's Adventures of The Black Cauldron. he returns again but only in a side story in Ryan, Winnie The Pooh & The Gang Meet Lilo & Stitch)
His partner in crime (in his opinion, a protege') was Ratigan, his soul slave because Fagin revived Ratigan with dark spawn magic, which makes Ratigan Fagin's enternal slave. Fagin often gloats that he has a higher evil status (which he does, he is a dark spawn villain) over Ratigan. But Ratigan does have his new position as Air Marshal of KOMPLEX's forces due to the orginal air marshal's death. however, whether Fagin will learn of this or will even treat Ratigan better if he does is currently uncerten.
Fagin comes from the movie War of the Birds, a danish, graphic, animated film.