Bento is just a good looking, very functional, flexible, basic flatfile-type database (a "lists" database). Nothing relational about it. What it does it seems to do very well, including hooks into Address Book and iCal (one of its nicest features, IMO).
I can't see it doing what you are looking to do, though. Not that you couldn't make it work. Just that there are software packages designed specifically for writers working on books, novels, etc. which seem to me like they would suit your needs far better. Google StoryMill or Scrivener, they are designed to do exactly what you need (StoryMill does character databases, timelines, etc.)
Along similar lines I'm trying the demo of OmniOutliner as a way of organizing flexible information that doesn't fit neatly in a relational database, but the demo licensing terms are a little screwy.