Series

So I just bought Dennis Lehane's Moonlight Mile, and I'm terrified to start reading it. Why you might ask, or maybe you'd ask how's the weather, I don't know you that well...anyway, at one point in time, Dennis Lehane was my favorite author. He had a gritty, dark, and loving mystery/crime series surrounding two PI characters, Patrick Kenzie and Angela Genaro. You might remember them from the movie Gone, Baby, Gone. I loved these books, and then suddenly, the two are broken in Prayers for Rain, and he starts writing other standalone books. That to be honest aren't great. I never worried about what was happening on Shutter Island.

Now Patrick Kenzie and Angela Genaro are back. And I'm scared I won't feel the same.

So those of you who write series novels, what makes you stay with a character? And what would make you do what Dennis did? For readers, how do you feel about series and when the series ends?