In the world of Harry Potter, May 2 is an important day. It’s when the Battle of Hogwarts took place. Not everyone survived the fight, however. Now, author JK Rowling has, as she did last year, come forward to apologize for the death of one character in particular. This year, it’s Remus Lupin.

“Once again, it’s the anniversary of the Battle of Hogwarts so, as promised, I shall apologize for a death. This year: Remus Lupin,” she wrote on Twitter.

She also reveals that she did not decide to kill Lupin, a Defense Against the Dark Arts teacher introduced in Prisoner of Azkaban, until after she finished writing Order of the Phoenix (via EW).

Rowling went on to say Lupin “had to die” because Arthur Weasley lived.

“I’m sorry. I didn’t enjoy doing it,” she said about killing Lupin. “The only time my editor ever saw me cry was over the fate of [Lupin’s son, Teddy].”

Lupin was killed in the Battle of Hogwarts by Antonin Dolohov, described as “one of the longest-serving, most devoted and sadistic of all Voldemort’s Death Eaters.” Lupin was played in the movies by David Thewlis.

In 2015, Rowling apologized for killing Fred Weasley during the Battle of Hogwarts. “Fred was the worst for me, so I started with him,” she said about her plan to mark the battle’s anniversary every year by recalling a character’s death.