Well it's actually a book Star Wars Lost Stars, it's a fantastic book that take place over the events of all 3 movies it also fills in some info about what happens after episode 6 and about the Battle of Jakku
https://www.amazon.com/Journey-Star-Wars-Force-Awakens/dp/1484724984
Get him the hard back cover to the book Lost Stars. It is currently the highest acclaimed Star Wars book out. He'll thank you with every chapter.
Then get him some other kind of accessory too.
I just read "Lost Stars" which is considered canon. They go very deep into how your average imperial soldier was recruited, what their motives were, and why some of them leave for the rebellion. It was a pretty good read, and it follows the timeline of the original trilogy.
Not sure if someone already mentioned Lost Stars, but it is a really good book that fits your request. It's the story about 2 imperial officers and their careers from the academy all the way through the end of ROTJ and beyond. It says "young adult" but it's a really good read.
Edit: And better yet, it's part of the new Canon
Have you read Lost Stars?
That one might change your mind.
I agree I didn't find it very young adult either but it is listed as a young adult novel:
http://starwars.wikia.com/wiki/Lost_Stars
It's also listed in the Young Adult category on Amazon:
http://www.amazon.co.uk/Journey-Star-Wars-Force-Awakens/dp/1484724984