My Fictional Friends

Two of the authors whom I early on followed are Sue Grafton http://www.suegrafton.com/ and Sara Paretsky http://www.saraparetsky.com/.   They both are mystery authors who have written a series based on a main character. Both had recurring characters who developed more or less. Because Grafton is a bit more prolific than Paretsky, her recurrent characters grew more.  For Graton's books, less so for Paretsky's, these additional characters were people I got to know.

When I started reading Susan Albert Wittig, I found a cast of recurrent characters who developed along with the main characters, and the community, in her series with herbs as a recurrent theme http://www.susanalbert.com/.  Partly because the stories were set in the Hill Country of Texas, some of which towns I know, and the characters of these towns being familiar, the stories felt very "at home" for me.  Additionally, Albert intentionally developed characters that we came to "know" as if they were real people. Witness, the introductions in the books that foster this perspective.

More recently, I have been introduced to Louise Penny http://www.louisepenny.com/, who writes about murder in Canada, typically set in a very small town, called Three Pines, but always involving residents who live in Three Pines.  The chief detective becomes friends with the residents of Three Pines, who are potential suspects.  This leads to one of the many tensions of the book because the chief inspector has blurred the boundaries.  I have grown to love the town of Three Pines, and the recurrent characters.  

When I read these books, I am transported to an environment in which I am sharing experiences with people I know, and perhaps, even friends. 

I have read other mystery series which include recurrent characters.  These characters do not always grow on me and become acquaintances as have the Albert and Penny characters. I like those people, and I think it would be nice to live in a small town with these people in my life.  
I think, for me, you could say these authors have achieved a great success.