- The Mortal Instruments series by Cassandra Clare - City of Bones, City of Ashes, City of Glass, City of Fallen Angels, City of Lost Souls.
- The Sookie Stackhouse series by Charlaine Harris - Dead Until Dark, Living Dead in Dallas, Club Dead, Dead to the World, Dead as a Doornail.
- The Harry Potter series by J.K. Rowling - Harry Potter and the...
- Bumped and Thumped by Megan McCafferty
- Matched, Crossed and Reached by Ally Condie
- Uglies, Pretties, Specials and Extras by Scott Westerfeld
And these are just some of the ones I can see from my desk. In fact, in my whole room, I can only see two series where the titles aren't connected to one another: The Hunger Games by Suzanne Collins (followed by Catching Fire and Mockingjay) and Patrick Ness' Chaos Walking trilogy, comprised of The Knife of Letting Go, The Ask and the Answer and Monsters of Men. I'm counting the Anita Blake series as related because they started off that way, I figure Laurell K. Hamilton just ran out.
And that's exactly the problem. If you're planning a trilogy or a sequel, naming that first book becomes that much harder if you're having to consider future titles as well. The book I'm about to start writing is tentatively titled One Previous Owner, and actually Two Previous Owners would be fine for the sequel. The problem is with book number three, where the pattern won't work. I'd say it doesn't matter, that the three can all have completely different titles and it won't make a speck of difference, but the data suggests otherwise. Is there a reason publishers prefer related titles? I suppose it makes branding easier.
But what about readers? Do you prefer series where the titles all work together? Have you ever even thought about it before?