Like the Spanish Inquisition before him, George R.R. Martin’s chief weapon is surprise. The author of the A Song of Ice and Fire series has packed his epic-fantasy novels with unpredictable plot twists — and for every shocking revelation, there’s an equally tantalizing secret that stays hidden, riddle that remains unsolved, or prophecy that has yet to be properly decoded. Game of Thrones, the show based on the books, has largely stayed away from Martin’s mix of hints, clues, visions, and red herrings, which is probably wise; no one wants a repeat of Lost, where fans went so berserk trying to figure out what was going to happen in advance that the show itself became an afterthought.

But readers have had almost two decades to pore over and ponder every line in Martin’s novels, beginning with the first volume, 1996’s A Game of Thrones. From Tumblr to Reddit to major ASOIAF fansites likewesteros.organd Tower of the Hand — as well as my and my co-author’s own sites All Leather Must Be Boiled and the Nerdstream Era, and our podcast, “The Boiled Leather Audio Hour” — self-taught experts and avid fans have advanced literally hundreds of theories about the past and future of the story, from slam-dunk analysis that’s been all but accepted as fact to tinfoil-hat crackpottery that makes the Kennedy assassination look as clear-cut as an episode of Murder, She Wrote. The sensation of stumbling across this incredibly vast trove of deep-cut knowledge for the first time is a memory many readers share: “Holy shit — Ned Stark isn’t Jon Snow’s dad?”

Below, you’ll find 50 of the most popular, compelling, convincing, and/or crazy theories out there. Consider it early prep for Game of Thrones’ sixth season, out in April. Dig in, but be warned: The Song will not remain the same.

With an editorial assist by our own Stefan Sasse, I wrote 10,000 words on 50 ASoIaF/GoT theories. This is the least sane thing I’ve ever been paid to do.