The plot of The Cursed Child is built around a Time Turner constructed in secret by the Malfoy familiy and what happened everytime the original history was altered. I believe in one of the timelines Cedric became a Death Eater.
Now, as to how canon is it? YMMV, but my headcanon is that Cursed Child is just fanfic written by Rita Skeeter
Now, as to how canon is it? YMMV, but my headcanon is that Cursed Child is just fanfic written by Rita Skeeter
"This is Master Obi-Wan Kenobi. I regret to report that both our Jedi Order and the Republic, have fallen with a dark shadow of the Empire rising to take their place. This message is a warning and a reminder for any surviving Jedi. Trust in The Force. Do not return to the Temple... that time has past. And our future is uncertain. We will each be challenged. Our trust. Our faith. Our friendships. But we must persevere. And in time, a new hope will emerge. May the Force be with you, always."