Alan Rickman as Severus Snape.Photo: Warner Bros./Courtesy Everett Collection

HARRY POTTER AND THE ORDER OF THE PHOENIX, Alan Rickman, 2007.

Excerpts fromAlan Rickman’s diaries are giving insight into the late actor’s role as Severus Snape in theHarry Potterfilm series and why he decided to continue playing the character amid tough times and desires to quit.

“Talking to [agent] Paul Lyon-Maris about HP exit, which he thinks will happen,” Rickman wrote in an entry dated Dec. 4, 2002. “But here we are in the project-collision area again. Reiterating no more HP. They don’t want to hear it.”

The actor decided to stay with the franchise, however, after he was diagnosed with an aggressive form of prostate cancer in 2005, ahead of filming forHarry Potter and the Order of the Phoenix, the franchise’s fifth installment.

After doctors opted to remove his entire prostate through surgery at a Tennessee hospital, Rickman wrote a journal entry detailing his decision to stay on as Snape in the beloved fantasy saga.

“Finally, yes to HP 5. The sensation is neither up nor down. The argument that wins is the one that says: ‘See it through. It’s your story,’ " he wrote.

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Dimitrios Kambouris/Getty

Actor Alan Rickman attends the New York Premiere of “A Little Chaos” at Museum of Modern Art on June 17, 2015 in New York City.

Rickmandied of pancreatic cancerin January 2016 at age 69. His diary entries, which span 25 years of his life, will be published as a book,Madly, Deeply: The Diaries of Alan Rickman, out next month.

“She nervously lets me in on a few glimpses of Snape’s background. Talking to her is talking to someone who lives these stories, not invents them,” Rickman wrote in 2000.

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In a 2007 entry, Rickman detailed his thoughts on Snape’s death inHarry Potter and the Deathly Hallows, writing that he had always known about the love story between his character and Harry’s mother, Lily Evans Potter.

" … I have finished reading the lastHarry Potterbook,” he said. “Snape dies heroically, Potter describes him to his children as one of the bravest men he ever knew and calls his son Albus Severus.”

“This was a genuine rite of passage,” Rickman continued. “One small piece of information from Jo Rowling seven years ago – Snape loved Lily – gave me a cliff edge to hang on to.”

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In one other excerpt, this time from March 2010, Rickman detailed the final day of filming the lastHarry Potterfilm alongside starDaniel Radcliffe.

“[I am asked] ‘So how does it feel?’ Before you’ve felt it, before the feeling has a name. ‘It’s private,’ I managed, ‘and I’m not sharing it with that’ pointing at his lens,” Rickman continued. “Something is in those cans and it is finished. Thanks, Jo.”

Madly, Deeply: The Diaries of Alan Rickmanwill hit shelves on Oct. 4.

source: people.com