How in the world do you finish a book series?

***WARNING: Spoilers ahead! No Mockingjay spoilers, but I do spoil the endings of Harry Potter, Twilight, The Age of Innocence and Lost. You have been warned!***

After finishing Mockingjay a day and a half ago (yes, I am STILL thinking about it!), I've been mulling over how various series have ended. Harry Potter. Percy Jackson. Lord of the Rings. Twilight... Actually, scratch Twilight. I never read Eclipse or Breaking Dawn and I don't know if I ever will. (Baby clawing out of Bella's belly? Uh, gross!)

Some of these series have ended with a bang.
Others with a sad sigh.
And others with a "WTF?! I wasted hours of my life for this?"

And I've been asking myself how. How do some authors write a satisfying ending to their beloved series? And how do other authors leave you with that disappointed and unsettled feeling after you've finished the last page? Is there some sort of special formula out there?

Here a few of the do's and don'ts I've thought of.

1.) Don't make it contrived. None of that "It was all a dream!" crap. Because then I will hate you FOREVAR!

Case in point: Lost. I know, I know, Lost isn't a book series but it was one of my favorite TV shows--and I absolutely abhorred the final episode. It made me angry actually. For the entire last season, I was led to believe that the parallel storyline was, you know, real. It was a place where the cast could continue on with their lives while their island counterparts died bizarre and awful deaths.

But then...the show pulled the rug from under me! The whole parallel storyline was some sort of afterlife where the cast could reunite as ghosts? What?! It didn't make any sense! First, aren't there easier ways to hook up in heaven? Like, asking an angel for assistance? And second, the twist simply blindsided me. There were no clues leading up to it. No hints. I needed something to help me bridge the gap to this afterlife conclusion. Instead, I was left treading in the water, wet and angry. Damn you, Lost!

2.) Don't tie up everything in a neat and pretty bow.

I think writers sometimes love their protagonists a little too much. I mean, I can't really blame them for that. After all, I would feel enormous sympathy for a character if I had written three or four or five books about him. BUT sometimes this sympathy goes too far and the author decides to write a happy ending for the protagonist because he's been through so much--and doesn't he deserve some happiness? And this, inevitably, leads to an unsatisfying ending.

You know where this is going, right?

Harry Potter.

Yep, the beloved HP. I do love me some HP and I think J.K. Rowling is bloody brilliant, but the ending to this series? Hmm, it just didn't ring true to me. It seemed like Rowling was holding back on the darkness because she didn't want to hurt Harry anymore. Didn't he deserve a break? How many more people could he bear to lose?

Yet in protecting Harry, Rowling lost me with the ending. It felt too shiny. The whole epilogue was like a dream sequence in Happy Harry-ville rather than reality. Because in reality, wouldn't Harry's oldest son have become a goth kid who despises his dad's celebrity status? And wouldn't Ron and Hermione have some marital problems because she's such a nag and he's such a lazy puss who doesn't aspire to anything outside of his boring Ministry of Magic job?

Or maybe I'm just a cynic...

3.) real.

If you've finished a novel, then you probably remember that strange feeling when your book becomes its own entity. All of a sudden, your characters start doing what they want to do and ignore your direction. Your plot meanders at its own discretion and your beloved characters get hurt or *gasp* even die. Somehow you, the author, becomes the medium who narrates the story rather than the one controlling it.

I think this is key in creating a satisfying ending. We as writers have to be true to where the story is leading us rather than impose where we want it to go.

For instance, The Age of Innocence by Edith Wharton. (It's totally not a series but bear with me!) At the very end of the novel, the protagonist Newland Archer has the opportunity to reunite with the woman who he has pined for for years, the Countess Olenska. Archer waits outside of her building in Paris...but he doesn't go in. He leaves. Not even a hello.

And here's the interesting part: Wharton initially wrote the scene so Archer and Olenska do reunite. After twenty years apart, they finally get back together. didn't feel right to Wharton. She tried and tried to make their reunion work, but it never came together. So, she finally let the story tell it how it was--which meant the two lovers never crossed paths again. It's an incredibly bittersweet ending, but I think it matches the tone of the book perfectly and it also wags its finger at the Victorian ideals that kept Archer and Olenska apart.

So what do y'all think? What makes for a satisfying ending? What are some series with satisfying endings? What are some series with endings that make you want to gnash your teeth?