The mermaids appear to be lazy, vain, shallow, and undeniably mischievous in nature. They are also fun loving and rather amoral, having no sense between right and wrong. This is especially evident with their reaction to Peter Pan scolding them for their harassing Wendy, where one of them casually stated they were "just trying to drown her." The mermaids seem to not have any real cares or troubles besides having a great fear of Captain Hook. They are all romantically infatuated with Peter Pan, who apparently visits the lagoon often to flirt and entertain them with his adventure stories. And similar to Tinker Bell, the mermaids are jealous when any other female catches Peter's attention.
The mermaids first appear in the 1953 animated movie when Peter takes Wendy to their turf to meet them. Wendy is ecstatic and enchanted by their beauty, for she has always dreamed of seeing and meeting real life mermaids. Wendy watches (or rather spies on) them from a safe distance as the mermaids lounge around on rocks to bask, bathe in waterfalls and brush their long hair and admire their own reflections in the shallow waters. They also seem to enjoy decorating their hair with random ornaments and adorning themselves with items from Neverland's surrounding ocean which leads into their lagoon. At first glance, the mermaids are all excited to see that Peter has come back to Neverland after his flight to London and is gracing them with his presence. After Peter says hello to them the mermaids ask him to tell them a story.
As they all gather around him to listen, he begins to tell them about the time he cut off Captain Hook's hand and threw it to the crocodile, but then they notice that he has brought a human girl along. They ask him why she is there in her nightgown, clearly suspicious. The mermaids then try to get Wendy to swim with them and begin pulling her into the water despite Wendy trying to inform them she is not properly dressed to join in.
The mermaids begin to splash her out of spite with their tails causing her to become soaking wet and upset to the point that she picks up a large sea shell nearby to throw at them in defense. Peter stops her in time, telling her that they were only having fun, to which one mermaid casually replies that they were "only trying to drown her." Suddenly, the entire lagoon's atmosphere becomes dark and gloomy, indicating an evil presence is close by. Sensing danger in the air and close at hand, Peter looks around and spots Captain Hook and Mr. Smee rowing by in a rowboat with the captured Indian princess Tiger Lily. Peter warns Wendy that Hook is coming. Upon overhearing his name, the mermaids scream and become frightened, prompting them to dive back into the water and deep under the lagoon to hide and disappear. The mermaids do not make another appearance in the rest of the film.