Like sequels to movies, it seems like a struggle for second books in the series to maintain the luster of the first. Mostly, the second book often seems to stall some.
Things that don't work (for me):
Slow dancing at arm's length apart syndrome-When the budding relationship from the first book comes to a stand still or divide for some explicable or sometimes inexplicable reason that almost always feels contrived.
Stuck in Depressionville syndrome-When the character is stuck somewhere for a long period of time with little progress made, no new information and/or seemingly no way out.
Back to square one syndrome-When the character loses whatever ground they gained toward their goal in the first novel. This sometimes happens (ugh) at the end of book one.
What does work (for me):
-When the main character ends up in a new kind of worse predicament (like the Hunger Games trilogy).
-Repeating patterns with new challenges plus growing conflict/info gained in an overall arc (like Harry Potter and Ally Carter's Gallagher Girl series)
-New POV characters and/or subplots becoming main plots (Like Maggie Stiefvater's Mercy Falls series).
-A large amount of new world building/backstory in the second book (Like Cassandra Clare's Immortal Instruments series).
-Same world, totally new story and characters (Like Kristin Cashore's Graceling series).
-And, the book I'm listening to right now managed to surprise me with a new strategy. It's Pandemonium, by Lauren Oliver:
The main character is in a worse kind of new predicament, like I've enjoyed in other books, but there is also some needed but potentially boring time spent in Depressionville.
The author, very cleverly, overcomes this predicament by going back and forth between two storylines/times. It caused a little confusion for me in the beginning (mainly because it had been so ling since I'd read/listened to the first book), but once I got into it I looked forward to the switching, and the melding of the two timelines occured seamlessly toward the end.
What about you? What works and doesn't work about second books in a series?