My friend and I conceived of a story, a world, and set of characters. We started an LLC partnership so that this IP is split evenly. We then decided person B would write a book based on the story we talked about. Would both our names go on the cover of the book, and then inside the book we detail that Person B wrote it, or would only the author go on front, and inside we say "Story by 'A' and 'B'" and then "Written By 'B " under that?
That's up to you. Think about what authorship means and discuss the consequences.
James Patterson, who has written many novels on his own, now only outlines the stories and lets other people write them. Yet he is named as the main author on the book covers. That is probably for marketing reasons, but it also means that he is perceived as the author of the book by the readers. They are his fans, and not fans of the actual writers. Also, Patterson alone owns the copyright (as indicated in the edition notices).
Writers Daniel James Abraham and Ty Franck publish under the joint pseudonym James S. A. Corey. No one knows how many ideas each of them has contributed or how many words each of them has written.
Other, usually celebrity "authors" have their books ghostwritten by someone who isn't mentioned anywhere in the book.
All these and many more options are open to you. Who actually wrote the book is largely irrelevant. What I would recommend is that the two of you
- decide how you want to present authorship to readers and media, that is, whose name is going to be the author brand name and will receive the accolades, and
- negotiate and sign a written contract both regarding copyright and royalties.
You might want to consult a lawyer if you think your book might become a bestseller and get turned into a movie or media franchise, that is, when lots of money and far reaching decisions might be involved.
In screenplays, there is a protocol for this.
They divide the task into "Story" and "Screenplay". The story is the development of the plot and the characters.
The "screenplay" is the actual writing of scenes and dialogue, specifying some special effects, etc.
Now, in a screenplay, the word "and" and the symbol "&" mean different things.
"And" indicates independent work. If the attribution reads "Story by Andy and Bill and Charlie", then in that order, Andy originated the story, later and without Andy, Bill worked on the story, and then later and without Andy or Bill, Charlie did the final work on the story.
On the other hand, "&" means they worked together. So "Story by Andy and Bill & Charlie", then Andy originated the story, and later without Andy, Bill & Charlie worked together to revise Andy's story.
Same rules for the Screenplay.
The exception in Hollywood is that if a work is done for hire, paid by a studio, then the studio gets credit for that work, not the writer they hired.
In print and novels, some authors do the same; devise stories and characters, and then hire writers they supervise and edit to produce the book. Depending on the contract, they may or may not give the ghost writer credit; many very good ghost writers are willing to take a big paycheck and maybe a share of royalties and give up attribution.
A similar thing happens in both comedy and song-writing; for many stars, their jokes or their songs, music and lyrics, are ghost-written, purchased and perhaps modified by the performing artist to fit their style.
In your case, the proper attribution would be "Story by Guy1 & Guy2, Screenplay by Guy2."
For a novel, you'd probably list "Story by Guy1 and Guy2" on the cover, and inside, "Story by Guy1 and Guy2, written by Guy1".
Personally, I think the story is the part that requires the most imagination and deserves the most credit. Writing is certainly a valuable skill and a critical contribution, nothing happens without a written work.
So this may just be my personal preference. I do both, and figuring out how to portray a scene isn't easy, but I feel the most creative and inspired when I am inventing the story. That's where I feel like most of the value in the story lies.
Congratulations on finishing a work, by the way, and don't alienate your writing partner by trying to hog most of the credit.