A Heartbreaking Work of Staggering Genius

At first I thought this book was a work of fiction. It seemed to be just a little too off the wall premise. A college-age kid suddenly is taking care of his younger brother. They relocate from Illinois to Berkeley, California. They manage to get places to rent by paying cash with their inheritance. He comes across as a young adult with the mind of 14 year old. Sex and nudity seem to be primary external preoccupations. He is totally not ready to take care of his brother. He seems to prefer that he be a little servant. His brother is not quite in to that. 

Dave does manage to help raise the brother. His siblings make occasional appearances. (They are older, but did not have the ability to take care of the younger brother.) Towards the end, there is more focus on his dalliances with a literary magazine  (he naively bankrolls it and has dreams of success.) and attempts to be on the real world. His "Story" seems to change a little each time it is told. There appears to be some degree of fictionalization in the novel. But don't we all "remember" things different ways? The style is where the work shines. It is very "gen-X".