RE: Ezio's progress in ASSASIN CREED BROTHERHOOD.

Yup the first book is actually about AC2. It adds more details on what happens during certain story segments and gives us a better timeline of events.

AC Brotherhood (Book) is a must read as it shows us what happens between certain end events that lead to the eventual confrontation with Ceasre. It also tells us what the apple showed Ezio!

Revelations is sort of the same with the book telling us how Ezio got to the point where the game began, and ends with his death which takes place in the movie embers.

Crusade which is a retelling of AC1 and Bloodlines also adds a lot more depth to Altair's story. We get to see him while he is in exile and what drove him to do some of the things we saw him do in Revelations.

From AC Forsaken ( a book that tells us what Haytham was up to during AC3 and is one of the best books in the series) to AC Unity the books change their formats and are instead told as journal entries!

The books are a must-read for any fan of the game!