I think that is up to them. I can imagine an author and editor producing a book and selling it on Fifobooks (my startup), and have an agreement between the two

I think that is up to them. I can imagine an author and editor producing a book and selling it on Fifobooks (my startup), and have an agreement between the two of them. I see it similar to cofounders launching a startup; they each bring something to the table and it is up to them to agree on a valuation/profit share.