‘Road Kill’ by Joe Haldeman
I am starting to sound like a stuck a record but again this is a science fiction story with very little interest in science fiction. A mentally-ill serial killer thinks he is an alien and eats the people he murders. This allows Haldeman to indulge in gratuitous torture porn for no reason. His other main character is a bloke called Spencer who is burdened with a preposterous life story that means no one could mistake him for anything other than a character in a story. The paths of these two obviously cross and they do so in a way that suggests staggering authorial laziness.
The shock twist at the end is that the serial killer actually is an alien. Which isn’t really shocking or twisty or any justification for writing this story. Lame.