Princess Piran is a fishy creature from the planet Aquitar.  She appears to be living in peace despite the reign of Black Shadow's general there, Perfect Dark.  Piran rescues Pico from Perfect Dark's water demons, then falls madly in love with him.  She becomes excited thinking that Pico had come to rescue her from the general.  Instead, she ends up protecting him, as Perfect Dark falls in love with him, too.