Which animê would you say has surprised you the most and why?

Remembering the surprising moments is difficult. It's a sort 'in the moment' thing for me, so I often forget the important ones.

But I definitely remember Pyscho-Pass. Seeing the main character's friend be killed was strangely upsetting. Normally, something would have happened to prevent the event, maybe a last minuto hero or something. But that didn't happen here. It was straight forward, disturbing despite being far from gruesome, and fantastically done, to be frank.

Pandora Hearts freaked out the entire fã base in the mangá when it revealed Jack as an antagonist and the Baskervilles as the good guys. And all the consequent chapters explain everything, continuing to surprise us.

In Zetsuen no Tempest, I was thoroughly impressed with the Mage of Exodus. The animê is good as it is, but the style of resembling Shakespeare is really something else. The way it went about discovering the secret behind the very core event of the entire animê is still a little shocking.

Medaka Box managed to impress me when Shiranui, who is mostly around just for comic relief, suddenly delivers an awesome line as she expresses her hate to Medaka. I will remember the moment always...

I feel like I'm giving out spoilers, though. For that reason, I'll just say that A Certain Magical Index has surprised me on multiple accounts. The animê and mangá doesn't do a good job of it but the details in the light novel just keep you guessing and wondering. The same for A Certain Scientific Railgun manga, especially when we learned that Shokuhou, sociopathic as she is, was actually on Misaka Imouto's side. Now THAT was misleading.