Death
Donnie: Why should I mourn for a rabbit like it was human?
Karen Pommeroy: Are you saying that the death of one species is less tragic than another?
Donnie: Of course. The rabbit's not like us. It has no history books, no photographs, no knowledge of sorrow or regret. I mean, I'm sorry, Miss Pommeroy. Don't get me wrong. You know, I like rabbits and all. They're cute and they're horny. And if you're cute and you're horny, then you're probably happy that you don't know who you are or why you're even alive. You just wanna have sex as many times as possible before you die. I just don't see the point in crying over a dead rabbit, you know, who never even feared death to begin with.
Karen Pommeroy: Are you saying that the death of one species is less tragic than another?
Donnie: Of course. The rabbit's not like us. It has no history books, no photographs, no knowledge of sorrow or regret. I mean, I'm sorry, Miss Pommeroy. Don't get me wrong. You know, I like rabbits and all. They're cute and they're horny. And if you're cute and you're horny, then you're probably happy that you don't know who you are or why you're even alive. You just wanna have sex as many times as possible before you die. I just don't see the point in crying over a dead rabbit, you know, who never even feared death to begin with.
In the film death is a prevailing theme. Early on in the movie Donnie narrowly escapes death, when the jet engine lands in his room. Donnie saved by his trance-like meeting of Frank. He will later learn is "the manipulated dead" according to the The Philosophy of Time Travel, and is tasked with helping Donnie resolve the tangent universe. This book was written by Roberta Sparrow, who at the time of the movie is a reclusive elderly woman known by the youth as "grandma death." She whispers to Donnie after a chance encounter that, "Every living creature dies alone." Something that Donnie takes painfully to heart.
As Donnie begins to realize that he will have to die, in order to end the tangent universe and save everyone. This is not news he takes easily and so trying to rationalize this has numerous conversations with his therapist and English teacher (Ms. Pommeroy). In all these conversations, such as the one above, he conveys his bleak outlook on death. He is clearly afraid that Frank is right, and that he will die, and without a theological belief in the afterlife, that it will simply end.
This is a struggle that Donnie faces throughout the movie, because he knows he has only 28 days to live. On a larger scale, the fear of death and dealing with loss is something that all people must do as we come of age. One of the hardest parts about growing up is losing people, particularly those closest to you. Most of us hope to live long lives, and the longer you live the more loss you experience. This realization of our own mortality generally occurs in our youth and may take some their whole lives to rationalize. Donnie was able to do this by the end of the film, however, that was arguably his whole life. Donnie, like most people, goes through the five stages of loss and grief, "1. Denial and Isolation 2. Anger 3. Bargaining 4. Depression 5. Acceptance" (Axelrod). This last one is evident in his letter to Roberta Sparrow, read as he finally closes the tangent universe:
"Dear Roberta Sparrow, I have reached the end of your book and there are so many things that I need to ask you. Sometimes I'm afraid of what you might tell me. Sometimes I'm afraid that you'll tell me that this is not a work of fiction. I can only hope that the answers will come to me in my sleep. I hope that when the world comes to an end, I can breathe a sigh of relief, because there will be so much to look forward to."
"Dear Roberta Sparrow, I have reached the end of your book and there are so many things that I need to ask you. Sometimes I'm afraid of what you might tell me. Sometimes I'm afraid that you'll tell me that this is not a work of fiction. I can only hope that the answers will come to me in my sleep. I hope that when the world comes to an end, I can breathe a sigh of relief, because there will be so much to look forward to."