How did Snape become a Death Eater?

Severus started at Hogwarts with Lily in 1971, where he was Sorted into Slytherin House. This put him in the same year as Lily but unfortunately for him in rival houses. ... In an attempt to win back Lily's affections, Snape joined the Death Eaters along with a group of his fellow Slytherins.

Why is Snape called the Half Blood Prince?

Family. Snape's family background is mostly shown in flashbacks during the course of the last three novels. Snape was born to Eileen Prince, a witch, and Tobias Snape, a Muggle, making him a half-blood (hence the name, "Half-Blood Prince").

What were Snape's first words to Harry?

The first thing Snape asks Harry is “Potter! What would I get if I added powdered root of asphodel to an infusion of wormwood?” According to Victorian Flower Language, asphodel is a type of lily meaning 'My regrets follow you to the grave' and wormwood means 'absence' and also typically symbolised bitter sorrow.

Does Voldemort know Snape is half blood?

Voldemort knew Snape was a Half-blood as for Snape's first kill, I believe the Dark Lord gave Severus permission to kill his own father which he gladly did. Voldemort also knew who Severus' mother was so therefore knew he was the last living relative of the Prince line.