If you’ve never read a book where the author seems to wish to abuse the reader, I would start with Infinite Jest. With about a hundred characters, both important and peripheral, and an index the reader must reference to grasp the totality of a world that takes place in the not-so-distant future, the sheer magnitude of the inner thoughts of addicts, involving drugs, sex, and a mysterious video cartridge, will pummel you. But you will keep asking for more. Completely unforgettable. You will emerge from this novel a better and stronger person.