|Family|| Ben Nicholson (father)|
Corinne Nicholson (mother)
The daughter of Ben and Corinne Nicholson, Katie was born with Williams syndrome, a rare form of mental disposition. Her family life was reasonably happy, but her father worked long hours and her mother resented having a daughter whom she felt would never grow up.
After Katie underwent heart surgery in April 2007, Corinne sought to escape from her problems and ended up in the arms of Joel Parven, the husband of her best friend Tina Parven and the father of a boy with Down syndrome. Joel and Tina were on the verge of separation, and he and Corinne began sleeping together. At some point, Corinne decided to try and get pregnant by Joel, eventually conceiving. Some time after that, Joel's son Alex learned about the affair.
The night that Joel decided to break things off with Corinne, Alex followed him, possibly just seeking to confront his father. However, Joel and Corinne ended up having sex one last time. Unbeknownst to all present, Ben Nicholson was at that time circling the building outside in a taxi. Ironically, he would later tell the detectives that he was circling the building because he felt sure that if he went in, he and Corinne would argue and end up filing for divorce the next day.
By the time Alex got to the Nicholsons' bedroom, Joel had left, and Corinne was alone. Alex grew enraged and savagely beat Corinne hard enough to put a crack in her skull, causing a brain hemorrhage. Katie had heard the whole thing and rushed to the bedroom. Finding her mother bleeding, Katie panicked and ran out of the apartment and into the street, barely escaping being run over by the taxi carrying her father.
It transpired that Ben was working for the Department of Homeland Security, which swooped in to stop the police from investigating him. This had the effect of making them more certain that Ben had been his wife's attacker, however, and when the feds refused to allow the police to investigate him, they reluctantly began to look to Katie for answers.
As it turned out, Katie's testimony pointed the detectives to Joel. Joel was brought in for a vocal lineup, but although Katie identified him as the man who had been having an affair with her mother, she reported that his voice was too deep to be the attacker. However, Joel had brought Alex with him, and as the Parvens and Nicholsons departed, Katie overheard Alex talking, recognized his voice from the night of the attack and ran to accost him for using the wrong word in calling her mother a bitch, unaware that in her attempt to correct Alex's vocabulary, she had identified the man who attacked her mother. Alex was subsequently arrested.
In trial, Joel fed his lawyer Chauncey Zeirko information about Katie's disabilities in attempt to discredit her testimony. His questions about her distance from her parents' bedroom and about the time of the attack badly rattled her, but ADA Casey Novak proved the question of distance to be irrelevant by showing that the distance between Katie's bedroom and her parents' bedroom was well within her earshot. Alex was convicted of all charges and sent to prison.
Abilities and Limitations
Katie has very poor spatial recognition abilities - she cannot accurately describe the size of a given object or tell you when something occurred - and hair-trigger emotions - she can be happy one moment and sad the next. She is also nearly incapable of lying (though she is capable of omitting things, albeit with a terrible poker face), and is naturally inclined to trust everyone. She is, however, highly empathic, able to pick up on the subtlest of facial or bodily cues, and has exceptional recall, though she has to put events and images into a semi-narrative sequence in order to accurately describe the order in which events occurred (usually marking the end of a sequence with the words "the end"). She is also extremely gifted aurally - she can recognize any voice and distinguish between voices - it was these abilities that enabled her to accurately identify Alex Parven as her mother's attacker. She can also remember anything that is said around her. Her hearing is highly sensitive and she can hear over great distances.