Instead of just establishing her as a Marine officer we see why she wanted to become one for she felt her life was going nowhere. Moreover, who can blame her? Her mom is a piece of shit and has no other friends or family in her life to fall back on. She has her dad whom she loves very much but isn’t available for her at the time of need. Because of all these factors, you can see why this woman wanted to get step out of her life and start anew.

Her only issue is that she is a train wreck. She begins to show complexity as the film goes on, but from the beginning of her voiceover monologue, she addresses to the audience how much she is not one for human interaction. As the film goes on to learn more about Leavy and why her character is this way. You side with her more and empathize with her actions.

When we're introduced to her dog Rex, we see him as a loose cannon. He is aggressive, impulsive, and listens to no one similar to Leavey. The only difference is that he barks. This dog is pretty much your typical teenage rebel. They don’t start off on the right foot, but over time you see them bond and come closer in a genuine fashion. They begin to have a genuine bond. For someone who says from the beginning how she is affectionate towards no one, you see her grow off elevator towards him especially after he saves her life on the battlefield. The dog becomes her home. You root for them to end up together because how her genuine their relationship is built. Their relationship feels real and never manipulative.