Why is marina so perceptive

Marina doesn't talk with anyone-she just observes. Marina was a fourteen year old girl, who was living in a boarding school. She suffers an acid attack in order to save her mother. The attack makes her quiet and she starts keeping things inside herself. In the boarding school, she doesn't talk to anyone. She doesn't make friends or play with her class mates. It was her English teacher who asked the class to keep diaries and the reader is introduced to Marina through those diaries. Otherwise, she was only a observer who was not involved in any action. Marina has shared the minute details in her diary about the people who surrounded her, their actions, their behaviors and their kind or unkind attitude towards her. After writing her diary, she starts making friends but she couldn't muster up the courage to talk to people. Her introvert nature doesn't allow her to share her feelings with others but she gets indulged in friendly relationships with her fellows.