Trilogies, a perfect set of three?

Having recently completed the final book in Nora Robert's newest trilogy, The Circle Trilogy, I found myself going back through some of her other trilogy/series. Most of are paperbacks; some with her current publisher Jove, and the older ones were Harlequin and/or Silhouette. Were I'm concerned, Nora Roberts could put her name on a cereal box and I'd buy it to read, same with Jayne Ann Krentz (or any of her other names) and Jennifer Crusie. Though the latter does not "do" trilogies, I did just buy her newest novella Hot Toy in a Christmas anthology Santa Baby. Anyway, after I finish a trilogy by a particular author I find myself compelled to go back through and read my favorite titles contained other trilogies they have published. I've noticed recently that most often, though not always, the book I am drawn to is the middle of the series. Consider these Nora Roberts titles:

• The Circle Trilogy
  Morrigan's Cross (2006), Dance of the Gods (2006), Valley of Silence (2006)
• In The Garden Trilogy
  Blue Dahlia (2004), Black Rose (2005), Red Lily (2005)
• Key Trilogy
  Key of Light (2003), Key of Knowledge (2003) , Key of Valor (2004)
• Three Sisters Trilogy
  Dance Upon the Air (2001), Heaven and Earth (2001), Face the Fire (2002)
• The Irish Trilogy
  Jewels of the Sun(1999), Tears of the Moon (2000), and Heart of the Sea (2000)
• Dream Trilogy
  Daring to Dream (1996), Holding the Dream (1997), Finding the Dream (1997)
• The Stars of Mithra
  Hidden Star ( 1997), Captive Star (1997), Secret Star ( 1998)
• The Concannon Sisters
  Born in Fire (1994), Born in Ice (1995), Born in Shame (1996)

... and these Jayne Ann Krentz titles:

• Eclipse Bay
  Eclipse Bay (2001), Dawn in Eclipse Bay (2001), Summer in Eclipse Bay (2002)
• The Curtain
  Amaryllis (1996), Zinnia (1997), Orchid (1998)

There are obviously more linked books than these, but they are nice sampling of what I mean. So I wonder, what is it about the magic number three? And, why do I usually like the middle book in the series. Keep in mind I am not an author and have no training either in the craft or as a reviewer of this genre of book. But it is my theory nonetheless. Here goes; I think the first book is "burdened" by setting up all three titles as well as having it's own story; the last book has to wrap everything up and stand alone; and this leaves the middle book free of obligations to do anything but tell a story. Obviously the theory is not without its flaws, in some instances I liked the first or last title best. And I haven't even touched on the magic of three within a single title like in The Three Fates or Montanna Sky. Regardless, I will be finishing Key of Valor this evening for the fifth or sixth time and will be saving my new Crusie for the weekend.

As long as these talented ladies keep writing, I'm a happy camper.

(Sigh, should it take four times for a post to publish? I think not!)

Tags: Romance novel trilogies, Nora Roberts, Jayne Ann Krentz, Jayne Castle, Romance novels, Romantic fiction, Great reads!