When we sit down in a theater to watch a movie, it’s easy to get swept up in the magic of what we see onscreen and forget how much time, effort, and frustrations may have gone into making the story come to life. For example, two actors may have been feuding for the entire shoot, but as soon as the director yells “Action” you’d never be able to tell.

Recently, a collection of Alan Rickman’s personal letters went up for auction, the contents of which reveal the late actor’s frustrations with playing one of the Harry Potter franchise’s most iconic characters: Severus Snape. Of course, playing the same character for eight movies is going to lead to some frustration at some point, but a letter from producer David Heyman hints that Rickman felt this way early on.

“Thank you for making HP2 a success,” writes Heyman. “I know, at times, you are frustrated but please know that you are an integral part of the films. And you are brilliant.”

Then, in a later note entitled “Inside Snape’s Head,” Rickman expressed his disagreement with how director David Yates handled his character in “Harry Potter and the Half-Blood Prince.”

“It’s as if David Yates has decided that this is not important in the scheme of things i.e. teen audience appeal,” writes the actor. While we may not know exactly what he is referring to, this letter confirms that his frustrations did not disappear after the second film.

Other letters from the collection shed light on the happier moments of playing Snape. Creator J.K. Rowling praised Rickman in one letter by saying that he was “doing justice” to her “most complex character.” In another, actor Daniel Radcliffe, who played the titular Harry Potter, said, “Thank you for all of my presents, I can’t wait to read Catcher in the Rye.”

The rest of the auction collection, which has been valued at around $1.2 million, includes 35 boxes of personal items, diaries, scripts, and letters from the likes of Prince Charles, Tony Blair, and Bill Clinton.