
In a misguided attempt to win back Lily's affections, Snape joined the Death Eaters along with a group of his fellow Slytherins.

This put his friendship with Lily, a Muggle-born, under great strain until it was eventually broken in their fifth year. Snape became involved with the bullies in Slytherin House, many of whom were pure-blood supremacists. Snape, when young, developed a passion for the Dark Arts, which increased as his desire for revenge against his bullies grew stronger. This led him to be irritable towards James's son Harry when he was a professor. Severus became the immediate enemy of James Potter and Sirius Black and was a frequent victim of their bullying. This put him in the same year as Lily but unfortunately for him she was sorted into Gryffindor House. Severus started at Hogwarts with Lily in 1971, where he was sorted into Slytherin House. He fell deeply in love with Lily upon their meeting and became a close friend of hers. He met Lily and Petunia Evans when he was nine. The only child of Muggle Tobias Snape and witch Eileen Snape (née Prince), Severus was raised in the Muggle dwelling of Spinner's End, which was in close proximity to the home of the Evans family, though in a poorer area. His double life played an extremely important role in both of the Wizarding Wars against Voldemort. Professor Severus Snape ( 9 January 1960 – ) was an English half-blood wizard serving as Potions Master (1981-1996), Head of Slytherin House (1981-1997), Defence Against the Dark Arts professor (1996-1997), and Headmaster (1997-1998) of the Hogwarts School of Witchcraft and Wizardry as well as a member of the Order of the Phoenix and a Death Eater.

Albus Dumbledore: " After all this time?" Severus Snape: " Always." - Severus Snape's love for Lily Evans
