Background: Born the second child in an obviously failing marriage, Rhea is well aware that she was her parent's last ditch attempt at staying together. That or an accident, given the fact that her sister is fourteen years older than she is. As such, she's taken on the responsibility for not being able to save her parent's marriage, blaming herself for her father walking out when she was six. If she had been better, wouldn't he have wanted to stay? If not for her mother, then for her at least?
Her sister had left by then too, leaving her alone with her mother for the next twelve years and nothing to do but study endlessly as her mother broke down. As a child, she was a disappointment to her father and the reason her mother cried - so she would be better. She studied sports scientifically, trying to perfect every game through hours of after school study. Her classes were things she would agonize over, studying every single textbook in the library, examining her teachers to try and guess what they'd want from essays and, most importantly, plotting out her life according to what her mother would like her to be. As difficult as it would be to fix a broken heart, well, she could study it up and try couldn't she? She could be better, so much better than her mother would have expected, so much better that her mother would forget him.
Her life was more or less totally plotted out according to what she thought her mother would like - except for summers, when her friend from Mexico would come over to visit and she would allow herself to act like a child. He stopped coming eventually and she fell out of touch with him, losing the only person she felt like she could act her age around. She went back to trying to be a prodigy.
University progressed in much the same way, except with her specialising in anthropology, she could drop a lot of the extracurricular stuff she'd picked up in order to impress her family and focus on that. She graduated with honours, and moved on to become a grad student at a different university, working part-time in the British Museum.
...Or that's what her file says. But honestly, smart, moneyed Oxford graduate, with the ability to conform to what people like and get people to let their guard down around her? She was headhunted whilst still in university, but not by AM. British Military Intelligence, section 6, the Secret Intelligence Service. After graduating, she was kicked straight into training, which was all very exciting. She learned how to do things like gather intelligence from the smallest of clues, marksmanship and not crack under torture and all that other James Bond stuff as well as taught that she was her country's woman, to be used as her government saw fit.