Series?

I had intended to do a 1-shot with my Birthrite story. It was going to be an AU historical and I was going to be happy that my world-building was going for a good cause. The story itself didn't progress like that. Of course I watch a lot of the History Channel and got a few great ideas from their shows that I just had to incorporate. Never watch history when writing a historical. You'd think the 2 would mix but no.

Back to Birthrite. It became 2 stories. Then I thought, oh, but what about Gareth? And then there were 3. Now I'm thinking, as Book 2 takes shape, but what about poor Isadore? She has no story, and I feel bad for her. Eh, now it's a 4 book series. They each have their own ending, and will probably be able to be read on their own. At least that's what I'm aiming for. It worked in book 1, Raven's story!