Xavier doesn't like to read. Actually, that's not true. He does like to read, but only certain kinds of books. Books he can't define but he knows them when he sees them. Lately he's been reading The Outernet series by Steve Barlow and Steve Skidmore. From the first book in the series, Friend or Foe:
"When Jack's new laptop reveals itself to be a link to the "Outernet," an intergalactic communication device, his world turns upside down as he becomes involved with space travel, extraterrestrials, and an intergalactic war."
He's liking these books enough that he's reading them completely on his own and writing his required monthly book reports on them, completely on his own, which is pretty impressive, considering how much drama we had to go through before he found this series.
It's often hard to find boy-friendly books. I've come to realize that most of the books I've loved, I've loved because they spoke to me as a girl. There is definite gender bias in the young adult book market. Obviously a 12-year-old guy isn't going to want to read The Princess Diaries, but once he's done with Harry Potter, what's left?
Jon Scieszka, who really understands what guys like Xavier like to read, has put together a website called, appropriately enough, Guys Read.com, where you can find lists of books broken down by age (young, middle or older guys) or search for books you've liked to find recommendations for others that may appeal. He's also edited an anthology called Guys Write for Guys Read, which wasn't Xavier's cup of tea but might appeal to your guy.
Alternatively, you will never go wrong with one of Scieszka's own books. If you haven't found him yet, you should.