Harry tells Snape about "Padfoot" As he does, Harry sends tells him that "he has Padfoot at the place where it's hidden," which is meant to warn him about Sirius and the Ministry of Magic. Except this only works if you know who Padfoot is.
Dumbledore knew Sirius was innocent, he is the one who engineered his escape by hinting at Hermione on how to do it. The most likely answer to this question is that Dumbledore told Snape.
Snape was angry, because he hates Sirius, and horrified at the prospect of having to work with him, and perhaps still of the opinion that Sirius was working for Voldemort. He wasn't shocked to learn that Sirius was an animagus; as you say, he already knew.
Harry is grieving for Sirius, and he blames everyone, including himself, for Sirius' death. He blames Snape for not making it clear he intends to alert the Order of the Phoenix to check whether Voldemort has, in fact, captured Sirius.
Harry then goes to the headmaster's office and finds the Pensieve. The stone Pensieve lay in the cabinet where it had always been: Harry heaved it on to the desk and poured Snape's memories into the wide basin with its runic markings around the edge.
Draco Malfoy's mother Narcissa was cold, cunning and devoted to the Dark Lord. But she was also a mother, which meant she was willing to risk everything to make sure her son was safe. When Harry survived Voldemort's Killing Curse for the second time, Narcissa pretended he was dead so she could get to Draco.
He didn't tell him, because there was always a possibility of Voldemort peeking in Harry's mind and seeing that piece of information, because if voldy had learned that snape was a traitor, he would have killed him, and hid all the horcruxes into more safe places, that was the same reason why snape didn't gave harry the ...
Harry Potter: Stag
Harry's patronus is undoubtedly the most recognizable. The stag is first seen in Harry Potter and the Prisoner of Azkaban when it saves Harry and Sirius Black (Gary Oldman) from the dementors at the lake.
Bellatrix Lestrange Killed her own cousin, Sirius Black: She killed Sirius (who was her cousin) during the battle at the Department of Mysteries. She was remorseless and was cackling in glee after she had murdered Sirius.
It is hinted that he has done something that would inspire Harry to seek revenge, but it is not until Christmas that Harry learns that Sirius betrayed Harry's parents to Voldemort, then, when confronted by their friend Peter Pettigrew, killed Pettigrew and twelve incidental Muggles.
“A creature I wouldn't want to kiss . . . a spider!” Harry figures out the riddle, and realizes that a spider is about to attack. But what he doesn't realize is what I now believe: that the spider in the maze is Professor Snape, in his Animagus form. It is Spider/Snape who bears down on Cedric and Harry.
He didn't mention that Sirius was an Animagus to Dumbledore because he didn't want to admit to breaking his trust while at school. All in all, Remus did the most to help Harry and the wizarding world.
Harry inherits all of Sirius's possessions, including the house at Grimmauld Place, the house-elf Kreacher, and Buckbeak the Hippogriff.
The answer is that Sirius wanted to deflect attention from the real Secret-Keeper. He probably hoped Voldemort would go after him so he could steer attention away from Pettigrew.
Severus Snape is one of the most divisive characters in the entire "Harry Potter" series. He was a double agent, so many character details were kept a secret. His mother was a witch and his father was a Muggle, leading to the moniker "The Half-Blood Prince."
Remus functioned as the conscience of this group, but it was an occasionally faulty conscience. He did not approve of their relentless bullying of Severus Snape, but he loved James and Sirius so much, and was so grateful for their acceptance, that he did not always stand up to them as much as he knew he should.
Harry tried to use this spell himself. The first time was against Bellatrix after she had killed Sirius. His attempt was unsuccessful because, as Bellatrix mockingly explained: 'You need to really want to cause pain – to enjoy it – righteous anger won't hurt me for long…'
Draco's refusal to reveal Harry's identity to Bellatrix was not because he liked him. It was because he believed that Harry was the only chance they had at defeating Voldemort. At first, Draco admired and revered Voldemort until he threatened his family's safety.
I never read it as being the Killing Curse that killed him, but the veil, so it really annoys me that in the movie, they added "Avada Kedavra" and pretty much rendered the veil pointless.
1 Albatross
As the rarest Patronus in the Wizarding World possible, the Albatross represents an enormous bird that flies freely across any sea. This rare Patronus represents those who are simultaneously fearless, optimistic, happy-go-lucky, and ambitious.
Snape's secrecy is revealed to have been a mask and he has sacrificed being well-liked to be able to save Harry, all because of his love for Harry's dead mother: the only friend Snape ever had.
The reason that Lilly's death was a true sacrifice (as in she died though she needn't have) is the fact that Voldemort genuinely would have let her live if she had stepped aside and let him kill Harry. Snape convinced Voldemort to spare Lilly.
Later in the year, McGonagall duelled with Death Eater Alecto Carrow during the Battle in the Astronomy Tower and later learned of Snape's murder of Dumbledore. McGonagall was initially appointed as Headmistress, but was demoted after Voldemort took control of the school and placed Snape as Headmaster.
He finds out for sure immediately after Nagini's attack on Arthur Weasley. This night is significant in many ways. While Harry sleeps, he enters Nagini's mind.