Article snapshot taken from Wikipedia with creative commons attribution-sharealike license.
Give it a read and then ask your questions in the chat.
We can research this topic together.
The young Barnacle Boy is voiced by Burt Ward, the original Robin.
Biography
Barnacle Boy is depicted as being the undercredited and underappreciated younger sidekick of Mermaid Man, a famous elderly superhero noted for starring in a popular television series and stopping crime throughout Bikini Bottom. Grumpy and slightly ill-tempered, Barnacle Boy is notable for his brooding, moody disposition and exasperation with his partner's absentminded behavior as a result of old age, and even into his golden years Barnacle Boy is still treated in a juvenile fashion, coddled in an infantile way. With infuriation for this he temporarily betrays Mermaid Man to take on a more hostile antagonistic lifestyle, only to return at the episode's conclusion with the promise of being treated with greater dignity. It was revealed in one episode that he and his partner had originally been equipped with aquatic superhuman abilities through a chain of complex and intricate events during adolescence, dedicating their lives to battling crime as a result.
Like Mermaid Man, Barnacle Boy's feelings regarding SpongeBob SquarePants appear to be slightly mixed, as he has been involuntarily entangled into various predicaments or situations as a result of SpongeBob's presence. In the episode of his debut, Barnacle Boy loathed the nonstop pestering of his enthusiastic fan at his home retirement center to emerge from a retired lifestyle, only to be convinced through the presence of Patrick Star and SpongeBob that Bikini Bottom desperately required superheroes as protection against so-called "evils," thus rebooting their television series. In following episodes, Barnacle Boy seemed to develop a closer bond with his fanatics, inviting them to guard the superheroes' lair during a retreat, only to be further irritated by SpongeBob's boisterous and excitable enthusiasm in later episodes.