It seems the Harry Potter movies weren’t always such a magical experience. Newly discovered letters from the late Alan Rickman, who played Professor Severus Snape over the course of eight movies, reveal the actor at times felt “frustrated” with the character’s portrayal.

Neil Pearson Rare Books recently acquired Rickman’s archive and is releasing 38 boxes of notes, correspondences, photographs, diary entries, fan mail, and scripts as a collection for auction.

In one letter, Harry Potter producer David Heyman thanks Rickman for making 2002’s Harry Potter and the Chamber of Secrets “a success.” He adds, “I know, at times, you are frustrated, but please know that you are an integral part of the films. And you are brilliant.”

Rickman also wrote a note, called “Inside Snape’s Head,” about his work on 2009’s The Half-Blood Prince and hinted at frustrations with director David Yates. “It is as if David Y. has decided that this is not important in the scheme of things i.e. teen audience appeal,” he writes.

Valued at £950,000 (more than $1,260,000), the collection also includes notes from Harry Potter author J.K. Rowling and franchise star Daniel Radcliffe.

“Just back from weeks away and had to send a line about what you wrote in the souvenir programme for Hallows II. Made me very tearful,” Rowling writes to the actor, who died on Jan. 14, 2016 after a battle with cancer. “Thank *you* for doing justice to my most complex character…”

Radcliffe, meanwhile, penned a thank-you note for gifts he had received from Rickman, including a classic novel. “I can’t wait to read Catcher in the Rye,” he writes.

Rickman had considered his role of Snape as “a punctuation mark” to his life, as he told The Los Angeles Times in 2011, “because I would be doing other things but always come back to that, and I was always aware of my place in the story even as others around me were not.”

Heyman also noted at the time how sometimes “a director would tell Alan what to do in a scene, and he would say something like, ‘No I can’t do that — I know what is going to happen and you don’t.'”

It was after Rowling told Rickman the meaning behind his character’s “always” line that he understood the complexity of the character. “If you remember when I did the first film, she’d only written three or four books, so nobody knew where it was really going except her,” he told HitFix in 2011. “And it was important for her that I know something, but she only gave me a tiny piece of information which helped me think it was a more ambiguous route.”