According to reports, the word 'always' is a reference to a scene in the final Potter book, Harry Potter And The Deathly Hallows, when Snape reveals he is in love with his childhood friend, Potter's mother Lily.
The Daily Mail reported a 2011 interview in which Rickman admitted he'd been entrusted with the information well in advance of it being revealed by Rowling.
"She gave me one tiny, little, left-of-field piece of information that helped me think that he was more complicated and that the story was not going to be as straight down the line as everybody thought.
"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.
"And its 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."
Rowling had previously paid tribute to Rickman on Twitter, calling him "a magnificent actor" and saying the world had "lost a great talent".
She tweeted: "There are no words to express how shocked and devastated I am to hear of Alan Rickman's death. He was a magnificent actor & a wonderful man ... My thoughts are with Rima and the rest of Alan's family. We have all lost a great talent. They have lost part of their hearts (sic)"
During his career, Rickman - who had starring roles in Love Actually and Die Hard and Robin Hood: Prince Of Thieves among others - won a Bafta, a Golden Globe, an Emmy Award and a Screen Actors Guild Award.
- nzherald.co.nz and agencies
