All Snape has to do is remove the original memory or thought from his own mind, ensuring that no trace is left behind for Voldemort to follow. If there is nothing there to trip the red flag of doubt in Voldemort's mind, then there is no reason to suspect that Snape is hiding anything from him.
Voldemort trusted very few people. He openly despised some of his Death Eaters, even the loyal ones like Lucius Malfoy. However, there were a select few that had his trust, and whom he treated with respect. This included Bellatrix Lestrange and Severus Snape.
Voldemort told Snape he had been a faithful servant, but that he had to regrettably kill him, as he mistakenly believed he was the master of the Elder Wand, as Snape had killed Albus Dumbledore, its former owner the year prior, during the Battle of the Astronomy Tower.
How did Voldemort not know Snape was using occlumency?
As with a lot of other things, Voldemort was so sure of himself that he was convinced he could break through whatever defences others put up against him. And so, when he read Snape's mind, he was convinced that he could see his true thoughts despite his occlumency.
Pretty much everything he did was two-sided. Even in the alternate, Voldemort-flavoured reality we witnessed in Cursed Child, Snape was working undercover. He really was that committed to the double-agent life and, as he himself told Harry, being good at Occlumency was an essential part of the job.
Why Voldemort Never Discovered Snape’s True Loyalty ? (Harry Potter Theory)
Was Snape actually loyal to Voldemort?
When questioned by Bellatrix about his loyalties, Snape says he has been working for Voldemort ever since Voldemort's return, and explains his actions in the previous books in that light. He points out that gaining Dumbledore's trust and protection has kept him out of Azkaban and free to operate on Voldemort's behalf.
Snape's loyalty to Lily is not something that ever really ends; it follows him and informs many of his other alliances for his whole life. When Snape first meets Lily, he is desperate for a friend, for someone to relate to. He finds that in her.
His father was neglectful and sometimes abusive, which may have contributed to Snape's disdain for Muggles. At some point during his school years, he decided to reject his father's name entirely, giving himself the moniker "The Half-Blood Prince" with his mother's maiden name instead.
With effort, Snape was able to prevent Albus Dumbledore from learning the truth about his loyalties. Due to Snape's facade, Albus Dumbledore trusted Snape for reasons that were kept between them both until Snape murdered him.
He was the bravest man Harry ever knew. Every year J.K. Rowling has another apology to make on the Battle of Hogwarts anniversary. The major showdown between the forces of good and evil originally took place on May 2, 1998, when Voldemort was finally defeated.
The intent of the caster is a vital component of the spell. While Snape was still able to produce Avada Kedavra without any intent to kill, being a great wizard, the mix of hesitation and necessity probably resulted in the spell being blue.
He could not do so openly, because she was in a magical cage to protect her from harm. Despite the fact that Snape is a talented wizard, he took too long to protect himself – because he was not even attempting a defensive spell. He was collecting his strength to attack Nagini in her cage.
With the return of his Death Eaters at the end of Book Four, Voldemort declared that Snape had left their ranks forever. Conversely, Dumbledore went on declaring his undying trust in Snape. So Dumbledore was no more wrong than was Voldemort.
Of course, since Bellatrix doesn't trust Snape because he supposedly has his own agenda, and since she resents him for getting off the hook so easily while she had to rot in Azkaban, anybody would feel contempt to know that Snape lived there.
Did Snape know Harry was under the invisibility cloak?
Dumbledore was doing James a favour by helping him pass down the Invisibility Cloak to his son Harry. Snape definitely knew because in book 4 when Harry sees crouch in Snapes office, he's in his invisibility cloak. As soon as snape sees the golden egg and the map he says 'potters here' to mad eye. Potters here.
Although he wasn't turned into a werewolf, he did develop some wolfish tendencies such as a liking for very rare steaks. He married Fleur on 1 August 1997, although their wedding was disrupted by the arrival of Death Eaters following the fall of the Ministry of Magic.
Under the influence of her father, Dolores grew up despising her mother and brother for their lack of magical abilities. She was sorted into Slytherin House at Hogwarts School of Witchcraft and Wizardry and hated her time at the school due to never being given any positions of power.
At this point, McGonagall begins to gain the upper hand as it becomes clear he cannot further transfigure or counter her attack, so the only way he avoids it is by taking refuge behind a suit of armour that he forces in front of him.
Notably, Voldemort appeared to be entirely unaware of this split, as he later created a seventh Horcrux in his quest to have six, and continued to target Harry Potter despite him now holding part of Voldemort's own soul.
He hid them using the only thing that would work against Voldemort. He used Fidelius charm and after that even secret keeper was to be protected using that as Sirius said in PoA. The plan failed because wormtail who was their secret keeper betrayed them.
Snape and Lily were best friends at Hogwarts, but they met before that. As shown in Harry Potter and the Deathly Hallows Part 2, the two were originally neighbors, with Snape hailing from the wrong side of the tracks.
By Harry Potter and the Deathly Hallows, it's a stretch to call Draco a villain anymore. We just watched — or read — him struggle to reconcile his choices and morals in The Half-Blood Prince. He can no longer justify his actions, and is far more aware of the evil he was born and raised into.
