Mortality
One of the major themes of this film is mortality. Kathy, Tommy and Ruth and all of the other clones are faced with the fact that their lives will be short. Coming to grips with this is different for each of the characters and thus the point, that we all deal with our own death in different ways. Some fight for life, like Tommy, others seek forgiveness before it all ends because of their cruelty like Ruth and others are still at a distance from death, like Kathy as she has yet to begin to give her organs yet. Each character's journey reveals that life is tied to death, and love no matter how powerful a force between two people eventually will come to an end. How one deals with the inevitable is the purpose of this film. The fact that we will all die means that we all must live in a way in which we have come to terms with our mortality so, that we are not hindered by fear, regret or attempting to run away from the truth. But, instead decide to live in a way that makes the most of our time here on earth.
Love
Love is seen in different forms throughout the story. We encounter it with Kathy and Tommy as children and see their connection from a young age. We also watch as it is disposed of by Ruth who steals away time from the pair by taking Tommy for her own, not in love but out of a necessity to be the focal point. She, in the end, understands her cruelty to her friends, to people she loves she hurt so deeply. We watch as Tommy and Kathy begin to find their heartbeat together again, and we see that no obstacle can keep two people who are destined to be together apart, with the acceptance of death. Thus, love's message in this film is to wake up to your true love; don't fall asleep with lust because when you do, you will only awaken with less time to give your heart to the right person.
Morality
The whole world being set in a dystopian Britain shows us that morality is a major theme. If we have the science to create clones is it ethical to use it? Should we use it? Do the bodies that are created have a soul? These are just a few of the questions that are raised by the story. And the question of morality becomes more intimate when Ruth steals her best friend's love from her. Ruth is the embodiment of the Doubles we never get to see in the film. They simply take what they want when they want in order to ensure their survival. They don't spend time with their clones, they only harvest their organs and in the case of Tommy and Kathy, Ruth has metaphorically taken their hearts by stealing time from the both of them which is a deep crime against morality.
