Ophiuca speaks in a formal way, as such as when she becomes Queen Ophiuca, Luna speaks like her. She is shown to be rather manipulative and also has a high interest in shopping and money.
In the anime, Ophiuca preys on Luna's jealousy of Harp Note and her love for Mega Man, and they EM Wave Change and fight Mega Man. Even when she is transformed, however, she hasn't lost her love for Mega Man and spends most of the battle trying to embrace him (though in a somewhat violent way, constricting him when doing so). Luna later turns back to her normal self. Ophiuca herself later gains the ability to EM Wave Change with a device that Cygnus obtains and becomes Queen Ophuica to battle. Ophiuca later returns back to the FM Planet, after adapting to her new modern lifestyle, helping the other FM-ians' get what they need to survive.
In the games, Ophiuca used to be helping until she realizes her mistakes and tries to defeat Mr. King and Gemini before she dies.