Ms Rowling replied to a question from a fan:
I told Alan what lies behind the word 'always'. https://t.co/NHTJ5J6kxb— J.K. Rowling (@jk_rowling) January 18, 2016
Ms Rowling was alluding to a scene in Harry Potter And The Deathly Hallows where Professor Dumbledore asks Snape if he has "grown to care for the boy (Harry Potter), after all" and Snape then shows him his Patronus, which is a doe, a reflection of Lily Evans Potter. (Also Read: To Alan Rickman, With Love and Respect From Harry, Ron, Hermione)
When Dumbledore asks him, "All this time?," Snape's answer is, "Always," referring to his unrequited love for Lily, Harry's mother. In that moment, invoked from Snape's memory, both Harry and fans realise that their loathing for Snape is entirely misplaced. It is an epiphany in the Potter narrative.
Long back, when the Potter films and books were in the initial stages, Mr Rickman had told the media that to convince him to play the role Ms Rowling revealed to him that there is "more to Snape than an unchanging costume."
Alan Rickman, 69, lost a battle with cancer on January 14.