So too with Bella, her rationality isn't what makes her special.
It does seem to become progressively more relevant. While it isn't luminosity that made Bella a witch or Edward's pseudo soul-mate, those skills become relevant when she uses them to navigate the world from that starting point. We can see Luminosity diverge from canon as Bella makes sensible decisions. For example, I think she wiped out the whole plot line for book two while simultaneously navigating herself and the Cullens away from the most idiotic decisions they made in book 1.
"Luminosity" isn't Bella's only skill and it isn't responsible for determining her starting position but it is worth following her along as she models approximately sane decision making skills while encountering progressively more difficult challenges.
For example, I think she wiped out the whole plot line for book two
And book 3. And some major details of book 4, although she hasn't precluded the broad contour of the story.
In the vein of the Harry Potter and the Methods of Rationality discussion threads this is the place to discuss anything relating to Alicorn's Twilight fanfic Luminosity. The fanfic is also archived on Alicorn's own website <strike>(warning: white text on black background)</strike>.
Previous discussion is hidden so deeply within the first Methods of Rationality thread that it's difficult to find even if you already know it exists.
Similar to how Eliezer's fanfic popularizes material from his sequences Alicorn is using the insights from her Luminosity sequence.
Spoilers for the fanfic itself as well as the original novels need and should not be hidden, but spoiler protection still applies for any other works of fiction, except for Harry Potter and the Methods of Rationality chapters more than a week old so we can freely discuss similarities and differences.
EDIT: Post-ginormous-spoiler discussion should go to the second thread. (If you have any doubt on whether you have reached the spoiler in question you have not.)