Romy, orphaned by her parents' deaths, entered an arranged marriage with an Indian Rajah devoted to Kali. Facing ritual suttee upon his death—burned alive on his funeral pyre—she was rescued by Rigodon, who risked his life during the ceremony. She initially joined Willy Fog's global journey to find relatives in Singapore, but remained with the group upon learning they had died. Serving as a medic throughout the travels, her compassion and medical skills became vital to the group's cohesion.

Romy developed deep affection for Willy Fog. Upon their return to London, believing they had lost the wager and faced financial ruin, she proposed marriage to Fog, motivated by genuine love and mutual support in impending poverty. Her proposal inadvertently prompted Rigodon to realize their eastward travel gained a day, allowing them to reach the Reform Club in time to win.

After securing the wager, Romy offered to dissolve the engagement, deeming its original purpose fulfilled. Fog refused due to his own love and gratitude, and they married. In later adventures, she appears as Fog's wife, continuing to accompany him.

Physically, she is depicted as a purple, blue-grey, or black-furred panther or lioness. She typically wears a long dress or skirt, often barefoot with three-toed paws, though she occasionally dons footwear like red high heels. Her veil, black during the rescue, transitions to white for the remainder of the series.