When Severus was nine years of age (1969) he had seen Lily and Petunia playing at the playground. He saw Lily cast magic and informed her that she was a witch.
They then become friends.
In 1971 Severus and Lily entered Hogwarts School together. But they were separated into different houses. (Lily into Gryffindor and Severus in Slytherin)
Later in that year Voldemort (Few knew his true identity) began his first attacks.
“Snape knew more curses when he arrived at school than half the kids in the seventh year and he was part of a gang of Slytherins who nearly all turned out to be Death Eaters.” – Sirius Black. Sirius, James, Peter and Remus began taunting Severus during his first year.
In the sixth year, James, Sirius, Peter and Remus publicly embarrassed Severus. Lily attempted to defend him, instead he called her a mudblood. Severus tried to apologize and during their conversation says how he is fascinated with the Dark Arts. Lily leaves him appalled by his fascination. This may be the reason Lily marries James instead.
In 1978 Severus graduated from Hogwarts and in 1979 Severus became a Death Eater.
In 1980 Professor Trelawney applied for a job at Hogwarts for Divination Professor position. Trelawney tells Dumbledore of a prophecy to prove her skill about how the Dark Lord will be defeated by a boy born at the end of July. Severus overhears the prophecy and informs the Dark Lord.
On the 31st of July 1980 Harry Potter was born to James And Lily
Sometime in August Voldemort decided that Harry was the perfect match of the prophecy and marked the Potter family's death.
The Potter's went into hiding. The fidelius charm was cast upon their hiding spot and Pettigrew was chosen as the secret keeper.
Pettigrew betrayed the Potter family and told Voldemort.
At midnight Voldemort went into their cottage in Godric's hollow and murdered James Potter and then ventured into Harry's nursery to find Lily guarding him with his life. Voldemort went to kill Harry but Lily sacrificed her life for him. Voldemort tried to kill Harry but the spell rebounded off Harry and almost killed Voldemort. Love kept Harry alive.
If Severus had never told Voldemort about the prophecy Lily and James could be alive. Severus would have to find another way to prove his loyalty. DO YOU AGREE?
Information from the Harry Potter series.
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