Benjamin is Marina Del Ray's sidekick, but he is much nicer than Marina, even complimenting Alana. He often follows Marina, trying to help her. He is later seen pampering her, showing he is either a friend or a hired servant. He puts up with Marina's rants, though it is clear he takes no interest in them. When Marina steals Sebastian's job, by busting him to King Triton, he is put in her place as the girls' helper. Unfortunately, on his first day of the job, Ariel runs away and Benjamin swims off to tell Marina. Marina is trying to win the King's approval, but he doesn't listen until Attina breaks the news to the King herself. Marina then begs him for the key to her electric eel's cage, but he refuses to give it to her, notifying that she told him never to give it to her, in a fit of rage. However, Marina distracts him with "pretty fishies" and steals the key, releasing her eels to hunt Sebasian and Ariel.
At the end of the movie, he is sitting with Marina in jail and tells her "You can't just hurt people. Hurting is mean. We don't want to be mean, now do we?" She agrees, and they samba until the credits roll.
- He is considered the secondary antagonist, although he is the voice of reason to Marina Del Rey, telling her to give up her evil ways. He is also sweet and kind-hearted, unlike Marina.
- Benjamin is alike to Kronk from The Emperor's New Groove. Both are the sidekicks to villains attempting to get power, and accidentally giving them horrific ideas while trying to help them give up their malicious plans.
- Benjamin is also very similar to Winnie the Pooh. He has the same gentle mannerisms and is quite absent minded.