Some content in this article is derived from information featured in Harry Potter and the Cursed Child, and, as such, spoilers will be present.
Alternate realities are versions of the original universe in which different events have occurred, primarily due to disturbances created during time travelling.
Eloise Mintumble was a witch who time travelled from 1899 to 1402 for five days. Over her time there, she managed to change the life paths of several others which made it so twenty five of their descendants were never born, thereby creating an alternate reality.
Albus Potter and Scorpius Malfoy
Albus Potter and Scorpius Malfoy were two young wizards who travelled from 2020 to 1994 to try and stop Cedric Diggory from being killed by Lord Voldemort. Their trip created an alternate reality which put them both on a path to try and correct what they have done. Ultimately they create three timelines before finally going back to a future that is identical to the original timeline.
Around the summer of 2020, Harry Potter found a new time-turner. When Amos Diggory found out and eventually went round to Harry's home to beg him to use it to travel in time and save Cedric Diggory, Harry told him he could not meddle with time and Amos left angry. Albus Potter heard the conservation and following an argument with his father on 31 August 2020, he decided to help Amos and travel in time to save Cedric. The next day, he told his friend Scorpius Malfoy of the plan and they found a way to jump from the Hogwarts Express on their way to Hogwarts.
Albus Potter and Scorpius Malfoy travelled to the First Task where they pretended to be Durmstrang students. They accidentally met Hermione as a young girl who followed them, and when she noticed them intervening with Cedric's task, she thought Viktor Krum had set them up. She went to the Yule Ball with Ron instead, but without the catalyst of Ron's jealousy over Krum helping him acknowledge his own deeper feelings for Hermione, Ron and Hermione never fell in love and Ron danced with Padma Patil. They fell in love, married and had a son Panju Weasley instead. Therefore, Rose and Hugo Granger-Weasley never existed.
Hermione grew up to be a mean Defence Against the Dark Arts professor, while Ron grew up to be a solemn man. Albus persuaded the Sorting Hat to place him in Gryffindor, and so it did, while Scorpius remained in Slytherin. Cedric also still died in the timeline. They avoid each other for a week before they decide they have to fix the timeline. Albus believed that by humiliating Cedric at the Second Task- and also affirming Ron's feelings for Hermione- they would change the future to the way they had hoped. They then used the time-turner and travel to 24 February 1995.
Albus and Scorpius intervene with the Second Task and changed the future to another alternate timeline. They managed to save Cedric by over-inflating the Bubble-Head Charm so that he is floating above the lake in his swimsuit, accompanied by a large fireworks display affirming 'Ron Loves Hermione'. However, this led to Cedric joining the Death Eaters because he felt so humiliated by the tournament. During the Battle of Hogwarts, Cedric killed Neville Longbottom, preventing him from killing Nagini, which, in turn, ensured Voldemort was not killed and gave him the opportunity to kill Harry and win the war, taking over the wizarding world.
Due to Harry's death, Albus was erased from the timeline. Scorpius returned to the future alone and found Hogwarts now under the control of Dolores Umbridge. He eventually joined forces with a small resistance and with the help of Severus Snape, Ron and Hermione, they try to retrieve the original timeline. They time travel to the First Task and use a Shield Charm to stop the other Scorpius intervening.
When Scorpius, Ron and Hermione return to the future following their trip to the First Task, they found the timeline still very identical to the third timeline. They were attacked by Dementors, so Ron and Hermione sacrificed themselves to give Snape and Scorpius time to flee. Before they travel in time to the Second Task where their intervention would retrieve the original timeline, the Dementors find them again. Snape sacrifices his life so Scorpius would be able to flee. He time travels to the Second Task where his intervention retrieves the original timeline.
Albus and Scorpius decide to take the time turner and destroy it. They invite Delphi to the Owlery to help. Delphi steals the time turner and makes Albus and Scorpius travel back in time with her to the third task. She wants to try and save Cedric Diggory in the hope it would return Voldemort to life in the same way it happened in the third timeline.
Albus and Scorpius manage to trick her and steal the time turner back with the help of Cedric when he stumbles across them and thinks they are part of the tournament. When Cedric leaves, Delphi manages to get the time turner back and uses it to travel in time again.
They travel to 30 October 1981. Delphi leaves Albus and Scorpius who eventually find out they are by Godric's Hollow. They go the home of James and Lily Potter and see them going out for a walk with a one year old Harry. They think Delphi wants to save Voldemort by killing the Potters herself.
They decide they have to tell their parents in the future where they are and steal the blanket that belongs to Harry. They create a message on the blanket, treated with a substance that will only become visible when it is exposed to a potion that Albus would accidentally spill on the blanket before the time travel began, allowing Harry to read the message in the future. Draco tells everyone that his parents have a time turner, which they use to travel in time to October 31 1981. They find the children and Ginny realises that Delphi doesn't hope to kill the Potters herself, but actually wants to stop Voldemort trying to kill the Potters.
They decide to try and fool Delphi into thinking Harry is Voldemort and transfigure him to look like Voldemort. It works for a moment, but the appearance eventually fades away and reveals the truth. Delphi gets angry and duels Harry who is helped by his wife, son and friends. They apprehend Delphi who then sees Voldemort going to Godric's Hollow. She tries to get his attention but is stopped by Hermione and Draco. They stay and watch James and Lily die in the hope of finding closure before they all return to the future. They ultimately return to a future identical to the original timeline.
Behind the scenes
- Injuries acquired during time travel age up in a different manner than the time-traveller. When Albus Potter was injured after travelling twenty years in the past, his injury aged twenty years (according to Madam Pomfrey) even though Albus himself remained the same age. Similarly, Eloise Mintumble may have been injured when she was retrieved by her colleagues, ageing her up hundreds of years.
- Knowledge of the un-born is retained by the people who made the changes in the timeline. The fact that at least 25 people vanished due to Mintumble's time travel may have been known only because Mintumble looked for them, or her retrievers retained such knowledge.
- Unique in Mintumble's case is that time itself was messed up - days were shorter or longer. But the disparity is too great to be comparable with Albus and Scorpius' time travel adventure.