Mermaid is a member or Mr. S's X-Men. Mermaid is a former member of Daredevil's travelling thrill show (a circus). After seeking out Mr. S and joining the X-Men, Mermaid aided the worlds heroes in beating the Skrull and his armies. Years later Mermaid was among the X-Men who escorted the Wakanda civilization to their new home in the Savage Land. Mermaid then helped defend the new New York Torch from the church of Immortus.
Mermaid has a fish like tail instead of legs, making her unable to walk. However she can fly, "swimming" in the air.