I have explained it numeorus times... either my answer doesn't satisfy you in some way, which I'd be open to discussing further... or you're just choosing not to accept the answer... especially since other posters have at least gotten the main gist around this point of contention (even if they don't agree). Anytime the DM can decide the outcome of a failed roll with no restrictions outside... it must follow logically from the fiction (where he/she also decides what follows logically)... there is a higher probability that he will subvert the result (as opposed to a result that is clear cut, like you fail a climb check ... you fall) to go in the direction he wants the story to go in.
I don't understand what you mean by the word "subvert". How does this relate to the word "author"? What is being subverted?
I reiterate my point: if the material the GM has to work with (the mace, the effigies, whatever it might be) only comes into the game as a result of player action declarations and backstory authorship; and if the fictional context of the GM's narration, which constrains and shapes that narration, is the result of player action declarations; then how is this the same as GM pre-authorship?
Obviously, for any given set of events in a "fail forward"-style game, it is conceivable that a pre-authored game might produce the same set of results. At the extreme, for any given book that is deliberately written it is conceivable that the same text might be authored just by cutting up and arranging words from newspapers and magazines! But the process is different, and the experience of playing the game is different.
Look at the effigy example... the player created a tribe to lead and once the DM gets his hands on it (even though he had countless options that wouldn't have removed control of the player's created fiction from the players hands) The DM decides that what would logically follow from the fiction ... is that the very tribe that was player created and character driven/led is now subverted so that it is trying to kill the character... How is that not having the power to railroad the story in the direction you want to take it?
Who has been railroaded? What choice has been denied to the player?
It's not the GM who is forcing the player to engage with the tribe/cult - the
player chose to make the tribe/cult the focus of play. It's true that the tribe/cult is not behaving as the player (and PC) hoped - but that's because the check to influence the tribe/cult was
failed. (Which brings us back to the point from way upthread, that the word "fail" in "fail forward" is not a euphamism for
success.)
"No" to what exactly??... you pre-prepped a Dark Elf NPC... I mean you're stating it in the italics part of this very quote...
<snip>
You gave him a percentage chance (based on the Skill score of the PC) for the Dark Elf to appear in the terrain of the Abor-Alz... In a pre-prep campaign this is done all the time, though it is more likely to be based on independent variables as opposed to a skill check... for practical play purposes from the view of the players it serves the same purpose... creating a chance for the Dark Elf NPC the DM created to to appear.
I didn't decide in advance to introduce a dark elf. I wrote up a dark elf NPC, and had it in the folder with the dozens of other BW NPCs I have statted up. When a navigation check was failed I needed to narrate some adverse consequences for the PCs, and narrated a fouled waterhole which - upon examination - had been fouled by an elf. That point - during the course of actual play, in narrating the consequences within the fiction of a failed skill check - was when I decided that the dark elf was part of the fiction.
Just a note it was not at all clear that the failed check was what defined him as an antagonist... though I find this interesting since you state the Dark Elf only appears because of failed checks... so at what point can he appear and not be an antagonist?
There are any number of ways in which an NPC might appear. In
the last session of the campaign that we played, an NPC knight ("Dame Katerina of Urnst") was introduced into play initially to rub into the players that their PCs had spent the night sleeping on the filthy streets of the Keep on the Borderlands; and then she reappeared to defend her confessor against accusations that he is an evil priest of a death cult.
If there had been no failed check I might have introduced the dark elf in some other way. Or not. We'll never know, because that alternative possible world never came to pass!
So wait was it the failed check that made him an antagonist, your choice to make him an antagonist, the nature of Dark Elves (which is pre-written), or was it feasible for them to interact with the Dark Elf... all of these can't be true at the same time, so which one(s) determined the NPC's attitudes towards the PC's?
Of course they can all be true. Dark Elves make good antagonists (because of their Spite), especially for the elf PC in my game. That means that, if I want an NPC antagonist to figure as part of the narration of a failed check, a dark elf is a good candidate. And the fact that the dark elf appears as an antagonist doesn't mean that the PCs can't try and interact with him. They saw him escaping through the darkness, when he threw a knife at one of them. They could have called out and tried to speak: between them they have Intimidation, Persuasion and other social skills, any of which they might have tried to deploy. (Although, as it turns out, they didn't.)
Wait in your original post you stated that you had decided you wanted to use a Dark Elf NPC... so had you decided beforehand you wanted to use a Dark Elf NPC or not? If so, then how did you also create the Dark Elf NPC as content off the cuff due to a failure?
I have a lot of ideas about what I would like to use in my game. In my folder of notes I also have multiple hermit NPCs statted up, various monks and inquisitors, some heretic priests, some evil wizards, etc.
Some of them might get used; some won't.
This was [MENTION=205]TwoSix[/MENTION]'s point, upthread - having ideas about what might make for fun elements of the fiction isn't the same as preauthoring the fiction.