Siryn

Theresa Cassidy, also known as the enchanting Siryn, is the daughter of mutant Sean Cassidy (Banshee), from whom she inherited her sonic-based powers. She was raised in secret by her father's malignant cousin, Black Tom Cassidy, who concealed her true parentage for years and manipulated her into joining him in his criminal endeavors. This caused her to cross paths with the X-Men and meet her father. From then on, she started to frequent the Muir Island mutant research center. In this condition, she temporarily joined a gang of mutant outlaws by misfortune, the Fallen Angels