Going out fighting
There's a famous poem by Dylan Thomas that begins, "Do not go gentle into that good night. Old age should burn and rave at close of day." That's basically the type of novel The Last Days really is—it's even indicated by the title of the book. The novel's fundamental assumption is that Ptolemy does the right thing by facing his death with clarity, even if the truth is terrifying—after all, he doesn't get to live forever. He really does die.
Independence and autonomy
One undeniable fact of life for Ptolemy is made perfectly obvious by his atrocious living conditions: He can't continue on in life without real assistance from care-takers. This difficult transition is represented in Ptolemy's choice for clarity, even at the cost of his own life. He wants autonomy more than he wants to be alive. And yet, that doesn't stop him from needing real bodily help from Robyn. When Reggie dies, this theme really shines, because Ptolemy has to reckon his first-person perspective on his own death with his inability to fathom Reggie's death in his limited demented state. Ultimately, his reward for allowing others to help him is that he gets one more chance to do something serious with his life.
The drama of death
One thing about literature that has been well documented by thinkers and poets is that tragedy produces a sense of pain in the audience, a dual pain with pity for the victim of the tragedy, and also fear for the audience member who is having to face an uncomfortable fact of life. The Last Days treats death itself as the topic of discussion, exploring death through plot and also through language which demonstrates Ptolemy's deeply psychological need for clarity in his final days.
