. . . and I think it's great! As a reader, I love series. The opportunity for longer story arcs, and the chance to spend more time with intriguing characters, really increases my enjoyment of the books. It reminds me of the much longer historicals--novels in general--I loved back when I first began reading romances.
I also love writing series characters. It must be something about the way my mind works when I'm setting up my fictional world, but when my main characters begin to come to life for me, they tend to have strong links to a greater "family" of characters. They're not simply a hero and a heroine living in a vacuum, after all--they have lives before their story begins, and those lives are peopled with other characters. Those secondary characters might not have full-fledged lives when it's not their story, but as I write they begin to develop, too. Inevitably by the time one story is drawing to a close, another is beginning.
Sometimes those secondary characters start to clamor for their own story when I've not gone very far in my WIP; in fact, this is how I ended up writing my first spin-off. While writing the book that would eventually be The Hidden Heart, Nicholas Talbot kept trying to jump into the forefront of Rannulf FitzClifford's story. The only way I could shut him up in my mind (I know, that likely sounds pretty strange--and if it doesn't, you're probably a writer
Readers have told me they like that my books are connected; in fact, at times they've asked for certain characters to have their own books. Sometimes I've done it, but sometimes the character they suggest either hasn't come alive enough for me to create an entire story, or in other cases the character hasn't really, in my opinion, been hero or heroine material.
The new story I'm working on is a spin-off from the l'Eau Clair Chronicles. I'm enjoying the chance to revisit old friends from my previous books, although I had to chart out what everyone looks like and their ages, families, etc. at this point in time so I can keep the details straight. This book--big surprise--is the first of a (so far) three book series, but I'm leaving my options open. You never know if more stories might come to mind once I really get into these three books!