For some reason the idea of death as an entity in which you can become attached or even romantically involved in seems to be becoming a popular paranormal subject. Luckily the idea and often the implementation of said idea is often thoroughly entertaining, it is probably best not to examine the premise or reason for the entertainment value too deeply. =)
Pagan, the main character in Existence, is a girl who has been able to see "souls" for years but has no real idea why and she has never been able to speak to one. Then comes along Dank (his name is questionable but easily ignored). Pagan is a mature character and I think she handled herself well throughout the book, except for near the end. I felt she became extremely melodramatic regarding Dank and it called to mind a certain Bella character in New Moon. It felt somewhat out of character for Pagan and I wish she had been a bit stronger in this scenario. Her resulting decision after the melodrama was handled well, I just could have done with a little less crying/pining.
Dank being a "human" student and carrying on a relationship with another student was....confusing. Why exactly did he become "human"? This is never really clear, as with a few other elements of the story that remained ambiguous or confusing. Death's abilities and why he is answering to anyone are a couple other issues unexplained. I mean he is Death, but where is the further explanation?
The ending felt a bit rushed, but ended with quite a cliffhanger comment. It certainly made me intrigued. Overall the story was entertaining and a quick read.