Cedric's death is a major plot point in the stage play Harry Potter and the Cursed Child, in which Harry and Ginny Weasley's son Albus uses a Time-Turner and prevents Cedric's death.
The reason Albus and Scorpius use the Time-Turner is to bring back Cedric Diggory on Amos Diggory and Delphi's, who was originally thought to be his niece, request – which they succeeded in.
Cedric Diggory
It's a genuinely gut-wrenching moment but, thankfully, Robert Pattinson makes a return just mere minutes later. Cedric, like Lily and James, comes out of Voldemort's wand as a result of Priori Incantatem.
From then on, Cursed Child tells us that Delphi was given to a mean old witch named Euphemia Rowle to be raised as the battle went on. We all know what happened next: Voldemort and Bellatrix were killed and Rodolphus was sent to Azkaban.
Albus and Scorpius stop Cedric's victory at the tournament, preventing his death.
Albus ended up in Slytherin because he couldn't stop thinking about ending up in Slytherin, and so the Sorting Hat couldn't grasp anything other than his thoughts about being in Slytherin.
The three of them are alone in the train car when Rose blurts out the rumor that Scorpius is actually Voldemort's son, then she promptly leaves. But Albus stays, cementing his friendship with Scorpius for life.
Delphi was conceived from a liaison between Voldemort and Bellatrix. She was born at Malfoy Manor, shortly before the 1998 Battle of Hogwarts. As Bellatrix and Voldemort were both killed in the Battle and Bellatrix's husband Rodolphus was imprisoned at Azkaban, Delphi was raised by Euphemia Rowle, a Death Eater.
She meets young Albus Potter and leads him to believe she is the niece of Amos Diggory, and cousin to the long-dead Cedric Diggory. But in the play's third act, Delphi reveals herself to be the daughter of Voldemort and Bellatrix Lestrange. Fans were shocked, to say the least.
The biggest revelation in Harry Potter and the Cursed Child was that Lord Voldemort had a daughter with Bellatrix Lestrange, who was named Delphini.
The Heir of Hufflepuff was none other than Cedric Diggory, who was well on his way to fulfilling the prophecy of the Heir of Hufflepuff when he was tragically murdered by Peter Pettigrew.
For the simple answer: Cedric had to die simply because he was an inconvenience to Voldemort. Voldemort set up a very direct plan to be “reborn”, and he needed Harry. Cedric was not supposed to come along, so like Voldemort always does, he just got rid of him.
Cedric and Harry completed the Third Task together. Both took hold of the Triwizard Cup, which transported them to the Little Hangleton graveyard, where Cedric was murdered by Peter Pettigrew with the Killing Curse, on the orders of Lord Voldemort.
It is interesting also to note that Harry does not actually kill Pettigrew, but that Voldemort's gift kills him despite Harry's efforts to save him. Pettigrew's death is a reaction to his own attempt to kill, or at least, disable Harry, coupled with Voldemort's distrust of his own lieutenant.
Conclusively, “The Cursed Child,” although stated by Rowling was indeed canon, by many reasons and examples of how off-setting this book was compared to the rest of the series, it can be argued that this is not canon.
Bellatrix's husband, as well as her maternal step-father, Rodolphus Lestrange, survived the battle, but was sent to Azkaban for his crimes. This left the young Delphi an orphan as her father had been. Euphemia Rowle took Delphi in and raised her, allegedly only because she was offered a substantial amount of gold.
Delphini (better known as Delphi) is the main antagonist of Harry Potter and the Cursed Child. She is the secret daughter of Bellatrix Lestrange and Lord Voldemort.
Much like Harry and Teddy Lupin, Delphini grows up as an orphan because both of her parents passed away during the Battle of Hogwarts. Unlike Teddy, however, she grows up without a loving support system. Rodolphus was sent to Azkaban, leaving Delphini in the care of Euphemia Rowle.
Because to a pureblood fanatic like Bellatrix, Harry is a Mudblood because one of his parents (Lily Evans) was a Muggleborn. Anyone with Muggle ancestry is one, including Snape since his father was a Muggle (Tobias).
Before her death, Bellatrix secretly gave birth to an illegitimate daughter named Delphini, whom she conceived with her beloved master, Lord Voldemort. Delphini was conceived sometime after the Battle of the Department of Mysteries in 1996 and before the Skirmish at Malfoy Manor in 1998.
He has grown afraid of Harry's connection to Voldemort. Perhaps Voldemort, knowing Dumbledore's love for Harry, would possess Harry and provoke Dumbledore to kill him. So, Dumbledore attempted to avoid Harry throughout Book 5 for Harry's own good.
Because the biggest secret being kept inside the Princess Theatre is the secret love that the play's two young protagonists – Albus Severus Potter and Scorpius Malfoy – have for one another. We are not the first people to notice this, and certainly weren't the only ones talking about it at this weekend's opening gala.
Dumbledore reveals how thoroughly he loves Harry. Harry is brave, and Dumbledore is proud as any father would be. More than that, Dumbledore succumbs to a parent's weakness; he cares more about Harry's happiness and wellbeing than the wizarding world he is trying to protect.