I found the Gone series incredibly disturbing. Really not sure I'd recommend them for a 12 year old - and I'd certainly dissuade my own 12 year old from reading them (they get progressively worse as you go through IMO)
[Gone] the series is no more disturbing the The Hunger Games.
I totally disagree. It is much more adult and much darker. It contains a number of very adult themes as well. The first book, or couple of books are not too bad but they get progressively worse as the series go on.
My DC read the Hunger Games at 10; there is no way these books are suitable for a 10 year old.
Mine loves the Anthony Horowitz books especially the diamond brothers (first book is called the falcons malteser ) for something light hearted, and the Malorie Blackman Noughts and Crosses series. Quite heavy subject matter but she loves it. Both have reasonably priced box sets on book people at the moment.
So many teen/young adult books these days have really dark subject matter! I remember reading Virginia Andrews at that age, which I guess is dark, but some of this dystopian/sci fi stuff strikes me as very scary. Why so much of it? I was in Waterstones today looking at books for my 13 year old niece and came away with nothing, because it all looked so grim.