Because Benjamin has amnesia and wasn't raised on Earth, she's very naive and inexperienced with life and relationships. Also, she is mute in front of Art, thought Jimmy is not. However, Art was angry that Holly was admired and he was overlooked in a production they were in together. Because of that, he and Holly started fighting a lot and they broke up. His dancing hasn't been the same since.
Art is short-tempered, especially around Jimmy.
He doesn't have a lot of patience for Jimmy's ignorance about things. Still, he does come to care deeply about Jimmy, especially. Art doesn't realize that Benjamin and Jimmy are the same person, nor does he have any idea that Benjamin is actually a mermaid. He's torn between Holly, whom he still has very strong feelings for, and Benjamin, who is beautiful but has problems communicating with him. Shona Shona is a merman who was away from Earth since the 14th century and just recently returned to New York to find a mate.