Terry has pretty big abandonment issues, due to her mother's death and never knowing her father. Being shipped off to boarding school didn't help, and she started to compensate by drinking - yes, starting when she was thirteen. Ever since, alcohol has been her friend through good and bad times alike. On the other hand, she is still dying for father and mother figures; there's an emptiness inside her she doesn't know how to fill.
While she agreed to help her uncle on this one job, she was not happy about his life of crime. (Obviously, underage drinking is fine. She's Irish.) She believes in doing the right thing, even if she won't do it to get into Heaven. She might have been raised in a Catholic environment, but she isn't sure about this whole God thing.
With her peers, she tries to play it cool a lot. She's friendly and likes to have a good time, but if you piss her off, damn, she can be pissed. She doesn't tend to swear much, but when she does, it means she's probably going to need to walk away fairly soon, before she starts screaming.
She knows she's pretty, but she doesn't really expect it to get her anywhere. Being pretty hasn't done anything good for her so far. She is still quite self-conscious about her body, and a lot less confident about it than she likes to appear. She is predisposed to depression, although she doesn't know it yet.
Theresa possesses a sonic power she uses by modulating her vocal cords. She also has a minor psionic power she can only use in conjunction with her main power, in order to focus it.
Right now, she can scream in a way that allows her to shatter objects - and harm people, if she isn't careful. She can also amplify sound (drawing it over to her from a distance) or set up sonic buffer zones that stop sound from passing. She can also affect people's balance. Moreover, she is immune to her own powers, and any powers like them, and her throat and vocal cords and superhumanly strong in order to withstand using her powers, never mind using them over several hours.
But there are many things about her mutation she has yet to discover she can do, such as using the vibrations of her scream as a shield or as a carrier wave in order to fly, or focusing them into an intense beam that she can use as a sort of sonic lance. She might also find out how much more she can do to people than hurt them or make them dizzy: she can also make them nauseous, unconscious at the drop of a hat, or even use her voice to put them in a sort of hypnotic trance, allowing her to make them do what she wants - or even fall in complete adoration of her. She will also find out she's able to use her voice as a sonar, much like a bat would, if plunged in total darkness.
However, her throat is still her weakness. Her vocal cords could be damaged and rendered useless, and while her throat and vocal cords are extremely strong, she could still strain them.
Lock-picking, safecracking, singing, drinking, athletics.
Alcohol, boys, pop rock, ballads, mythology, movies and TV shows (teen drama ftw!), fitness.
Theresa never met her father, and isn't even sure how to go about finding him. She was raised by her uncle, Black Tom Cassidy, after her mother died in a RIRA bombing shortly after Terry's birth. Her father, Sean Cassidy, had been on an undercover Interpol assignment and did not even know that she existed. When he came to the funeral and confronted his cousin Tom about not protecting his wife, things became heated and Tom ended up with a broken leg before he could tell Sean that he had a daughter.
Angry with his cousin, Tom decided never to tell Sean and proceeded to raise Theresa on his own, telling her that he had no idea where her father was or how to get in touch. As she grew up, Theresa went through phases of rebelling against that and going along with it. In every way that mattered, 'Uncle Tom' was her father, and he raised her at Cassidy Keep with the help of the butler.
Uncle Tom also happened to have been a thief. He had put some money on the side and did not need to do any jobs during her childhood. But eventually, money began to run out. Terry was 13 when Tom decided to go back to the life. He protected her by sending her to boarding school.
Last year, Terry manifested. A shouting match she'd gotten into with a schoolmate ended with every window in the dorm shattered, and every girl on the floor, hands over their ears.
Tom pulled Theresa out of boarding school and took her with him to America. He had a big job planned, and with her newfound abilities, she might be able to help. So he brought her in, taught her for a few months, assured her that it was the last job he needed to pull and that he could become an honest man afterwards. They were going to crack a private owner's safe, and Tom said he had a fence lined up to fork it all over.
When things went badly, Tom made sure that Terry escaped by making her scream, but he was affected along with the cops and was caught. Theresa was left on her own. She went to his court hearing and heard him plead guilty and refuse to name his mutant accomplice, the one who'd floored everyone in the vicinity with a scream. When she walked out of the courtroom with tears in her eyes and no idea what to do next, a bald old man in a wheelchair was there with an offer.