Sequel Works which add Important Lore Rules which Never Appeared in the Original

Same with The Matrix. Fuck it, even John Wick.

The last Harry Potter book introduced this whole rule that beating another wizard makes you the new master of their wand, something that never came up before but was suddenly an essential rule for the plot.

There’s not the slightest inkling in Dune that resurrecting dead people via clones is a thing.

Isn’t that a technology that’s explicitly invented during the course of the books (not something that supposedly always existed but never was revealed)?

Early in “Buffy the Vampire Slayer” demons were all evil and were individuals - when they encountered a demon, they’d look into the record books and identify which demon it was (“Oh, that’s Gachnar; here’s the information about how to fight him!”). Rather suddenly, demons come in species, some good, some evil, some neutral, and now the heroes look up what kind of demon is being dealt with “Oh, that’s a Fyarl demon - here’s some information about what they are like”).

The reawakening of memories is something that was theorized to be possible and then achieved in the sequel.

The existence of gholas at all, though, is a tech that pre-exists the first novel, but isn’t mentioned at all in it (AFAICR)

Thanks. It’s been decades since I’ve read the books

That’s only for the Elder Wand.

Came to say this. I sat in the theater in 1989 wondering if I’d forgotten something from the first movie.

Well, he did rewrite history in the first film…

According to Jaws II, …III, and …IV, sharks get pissed and seek revenge when one of their kin gets killed by law enforcement (or their family).

Yeah, but that always just seemed like a hand wave to explain why the warp numbers are different in the TNG era.

This isn’t really a “lore rule” per se, but the word psychohistory is not mentioned in the very first Foundation story, “The Encyclopedists”. Salvor Hardin refers to “psychology” in the first story, but “psychohistory” isn’t mentioned until the second story -it’s also mentioned in the preface written in 1951 for the trilogy editions.

Interesting - I hadn’t noticed that.

I’ve missed the recent movies and I wasn’t aware of this one.

If I may add a literary example…

Lois McMaster Bujold wrote the novel Memory in 1996. In this novel her lead character, Miles Vorkosigan, was appointed the office of Imperial Auditor, which we are told is a really important job.

The problem is that Memory is the twelfth book in the series and Auditors were never mentioned before this one. So apparently it’s a really important job that nobody ever talked about.

To be fair, most of the earlier books’ actions took place off-world or while civil unrest made that important job less relevant, so that job wasn’t important to the plots of those books.

Another example is that in the later books, there’s a near-perfect truth serum, but that serum isn’t used in the early books, even when it would have been very useful (arguably, though, since the early books take place 20 years before the first mention of “fast-penta” we can imagine that it wasn’t invented at the time of “Shards of Honor”).

John Scalzi’s “Head On” is a sequel to his “Lock In” taking place about a year later. In the second book, we learn that there’s a very popular sport (with dozens of teams and a well-developed fan-base) involving beheading robots controlled by human players. The problem is that in the first book, there’s a scene in which a human controlling a robot is menaced by a mob of people who threaten to whack her head off with a baseball bat - but no one mentions the similarity to the sport which must exist at that point.

Yup. Between midichlorians, and “Jedi aren’t allowed to marry, or have other emotional attachments,” the Prequels added significant lore that was never even touched on in the original trilogy.

That’s true of some of the series but there were several books prior to Memory which took place on Barrayar and had political plots. Why didn’t anybody mention what the Auditors were doing during Vordarian’s civil war, for example? The obvious answer is because Bujold hadn’t invented them yet. But when you go back and reread the early books in the series after seeing where it went to, the gaps are noticeable.

If you want to approach this from another direction, in an early work (Shards of Honor I think) a character mentions some planets that might be responsible for launching an invasion; Barrayar, Cetaganda, and Nouvo Brazil. Barrayar and Cetaganda would of course appear in many future books in the series. But Bujold never mentioned Nouvo Brazil again, even in books about interplanetary politics and wars. Somehow a planet that was considered a major threat to other planets disappeared. At the very least Bujold could have had a throwaway line about Nouvo Brazil having a civil war and being reduced to an insignificant power.

When there’s a civil war going on, the Auditors’ ability to take action is probably pretty limited - but there should have been a mention that Vordarian had captured or killed a few Auditors.

“Warrior’s Apprentice” implies that Ivan’s father’s death was relatively recent, but “Barrayar” (taking place before, but published after) changes that significantly, which was jarring for me, since I read WA just days after reading Barrayar. Totally forgot about Nouvo Brazil.