Leon - the Professional

Léon (Jean Reno) is a lonely and emotionally detached hitman. He lives a solitary life and spends his time watching musicals in between training and taking assassin jobs for Italian mobster Tony (Danny Aiello). Léon is seen in a cinema, watching a musical with faint amazement at the joie de vivre depicted by the film's characters, something he himself is unable to express. He meets Mathilda (Natalie Portman), a twelve-year-old girl who lives with an abusive family in the same apartment building. After corrupt DEA agents, headed by agent Norman Stansfield (Gary Oldman), kill Mathilda's family, Léon saves Mathilda by grudgingly opening his apartment door to let her in with her groceries.

Mathilda then pressures Léon into taking her in, since she has nowhere to go. She tries to persuade him to teach her his trade so she can avenge her brother's murder. In return, she offers herself to do all his house work. After an initial one night stay at his apartment, Léon accepts her offer. Working together, the two slowly build an emotional attachment to each other, with Léon becoming both Mathilda's friend and also a father figure. In taking care of her, Léon begins to find something more meaningful in his life than his job.

Wiki'ed!

Mathilda: Leon, what exactly do you do for a living?
Léon: [Leon] Cleaner.
Mathilda: You mean you're a hit man?
Léon: [reluctantly] Yeah.
Mathilda: Cool. 

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"The rifle is the first weapon you learn how to use, because it lets you keep your distance from the client. The closer you get to being a pro, the closer you can get to the client. The knife, for example, is the last thing you learn."