Orphaned by the massacre of her whole family, Mathilda is forced to take shelter in Leon’s apartment, which she barely knows. Despite the idea that he has never had reason to care about anyone but himself, he is forced to let her in. This is the beginning of seeing Leon sensitivity and showing feeling of care for other. Together they form father and daughter relationship that changes both their lives forever. He teaches her the skills of “cleaning” so that she can take her revenge for the death of her brother. She accompanies him during his duties, learning and doing what he asks of her. As he survives with Mathilda, he gradually begins to discover the reason of living for someone. He begins to realize and feel more attached to Mathilda as she is able to express her feelings of love and admiration towards him without embarrassment.
Although it is portrayed that Mathilda is sexually attracted to Leon, it is clear that Mathilda is not sexually attracted to Leon, nor is Leon sexually attracted to her. However, Mathilda desperately wants to express her love for Leon and thinks that sex is the best way to do it. She's not uncomfortable with the idea of sex because it's about finding someone that can express love to her and love her back, not sex. Leon initially refuses and makes attempts to avoid her expressive character for fear of experiencing that level of intimacy again, and he is uncomfortable with the idea of having sex with a 12 year old girl. Nonetheless, the attachment bond continues