Aristotle, I guess. A story is defined by one character who struggles to achieve a goal and transforms in the process; however, a plot can contain multiple stories, and each one can have its own protagonist. Also, a story can have an ensemble protagonist, where a group of people fulfill the protagonist role, e.g.…

We've got the Movie coming up. How anyone can like that monumentalist rubbish puzzled even my 14 year-old self.

Of course, before that, the official story was that the Doctor was *definitely* the only Time Lord in the universe. If there were others, he would Know.

S3 is when they hired Ronald Moore. To the extent that this applies to the DS9 debate… 'nuff said.