Why did Harry Potter trust Snape?

Question

In Harry Potter and the Deathly Hallows, when a dying Snape gives his memories to Harry, why does he trust Snape, of all people, and go to the Pensieve to see them? There are two possible scenarios (in which Snape is still on the dark side) where everything can go wrong:

1. It was all a ruse.

   Malfoy could have told Snape about him disarming Dumbledore, and Snape could have told Voldemort about winning wands by disarming (supposing he knew about it, as an experienced wizard). So Voldemort could easily have won the wand from Snape. Supposing Snape's "death" was all Voldemort's illusion (I know magical illusions have never been mentioned, but hey) and Voldemort was lying in wait, in Dumbledore's office, for an ambush. Or Snape's memories were actually modified, and there was no need for Harry to die. In which case they were meant to lure Harry to the forest to his death. Voldemort's calling him to the forest corroborates with this.

2. Snape might actually have been dying, but, still loyal to Voldemort.

   He could have tampered with his memories, to send Harry needlessly to his death. It sounds like the sort of thing Bellatrix Lestrange would do, but there you go. For all Harry knew, Snape was just as dedicated a Death Eater as she was.

So that's my question. If Snape was on the dark side, both of these possibilities could have resulted in Harry's death. So why did he trust him, again, of all people?

Answer 1

There are several factors that would lead Harry to believe that this was real and not a ruse.

• Dumbledore had always maintained that Snape was on their side.

  Throughout the four final books of the series Dumbledore constantly affirmed that Snape was on their side. Even when repeatedly questioned on this by his underlings (including Harry) he never budged one iota. Not only that, he never divulged the reason that he trusted Snape. He simply stated that he trusts Snape absolutely and refused to discuss the matter further. For example, on the very day that Snape killed him, Dumbledore discussed this with Harry:

  "But he's a very good Occlumens, isn't he, sir?" said Harry, whose voice was shaking with the effort of keeping it steady. "And isn't Voldemort convinced that Snape's on his side, even now? Professor... how can you be sure Snape's on our side?"

  Dumbledore did not speak for a moment; he looked as though he was trying to make up his mind about something. At last he said, "I am sure. I trust Severus Snape completely."

  After Snape killed Dumbledore, people couldn't understand how Dumbledore could have been so wrong. Note the following discussion shortly after Dumbledore's death:

  "Snape," repeated McGonagall faintly, falling into the chair. "We all wondered... but he trusted... always... Snape... I can't believe it...."

  "Snape was a highly accomplished Occlumens," said Lupin, his voice uncharacteristically harsh. "We always knew that."

  "But Dumbledore swore he was on our side!" whispered Tonks. "I always thought Dumbledore must know something about Snape that we didn't...."

  "He always hinted that he had an ironclad reason for trusting Snape," muttered Professor McGonagall, now dabbing at the corners of her leaking eyes with a tartan-edged handkerchief. "I mean... with Snape's history... of course people were bound to wonder... but Dumbledore told me explicitly that Snape's repentance was absolutely genuine.... Wouldn't hear a word against him!"

  "I'd love to know what Snape told him to convince him," said Tonks.

  "I know," said Harry, and they all turned to look at him. "Snape passed Voldemort the information that made Voldemort hunt down my mum and dad. Then Snape told Dumbledore he hadn't realized what he was doing, he was really sorry he'd done it, sorry that they were dead."

  They all stared at him.

  "And Dumbledore believed that?" said Lupin incredulously. "Dumbledore believed Snape was sorry James was dead? Snape hated James...."

  "And he didn't think my mother was worth a damn either," said Harry, "because she was Muggle-born.... 'Mudblood,' he called her...."

  As seen here everyone is confused about how Dumbledore could have been so wrong, and they assume that Dumbledore had a secret reason for trusting Snape, and when Harry suggests a reason Lupin ridicules it as being a horrible reason to trust Snape.

  So Harry was well aware that something didn't add up. There had to be more to the story. Snape's memories explain everything perfectly. It all makes sense now. Dumbledore had a very good reason for trusting Snape after all, and Snape had not actually betrayed him. Harry is willing to accept this because it finally makes all the facts fit together.

• Snape and Voldemort didn't know Harry was there.

  Voldemort killed Snape in the Shrieking Shack. Neither of them knew that Harry was present, so there would have been no reason for it to be a ruse to trick him. Harry figured out where they were by reading Voldemort's mind:

  "You need to find out where Voldemort is, because he'll have the snake with him, won't he? Do it, Harry — look inside him!"

  With a gasp, Harry pulled back and opened his eyes; at the same moment his ears were assaulted with the screeches and cries, the smashes and bangs of battle.

  He's in the Shrieking Shack. The snake's with him, it's got some sort of magical protection around it. He's just sent Lucius Malfoy to find Snape.

  Harry put on the Invisibility Cloak before approaching the room that Snape and Voldemort were in:

  At last the tunnel began to slope upward and Harry saw a sliver of light ahead. Hermione tugged at his ankle.

  "The Cloak!" she whispered. "Put the Cloak on!"

  Harry assumed that Snape and Voldemort were unaware of his presence, thus, their conversation could not have been fabricated in order to trick him. Once Harry does reveal himself to Snape there would have been no time for Snape to create a whole slew of fake memories on the spot, especially considering he was in the process of dying.

• Harry himself wasn't sure why he was approaching Snape.

  He did not know why he was doing it, why he was approaching the dying man: he did not know what he felt as he saw Snape's white face, and the fingers trying to staunch the bloody wound at his neck.

Answer 2

Because of the Silver Doe

All the other points made are correct, so I will not repeat them here.

Of all the memories Harry saw in the Pensieve, there was a specific one that Snape wouldn't be able to know, if he wasn't part of it: the silver doe that led Harry find the sword of Godric Gryffindor.

‘For him?’ shouted Snape. ‘Expecto patronum!’

From the tip of his wand burst the silver doe: she landed on the office floor, bounded once across the office and soared out of the window. Dumbledore watched her fly away, and as her silvery glow faded he turned back to Snape, and his eyes were full of tears.

‘After all this time?’

‘Always,’ said Snape.

_{Harry Potter and the Deathly Hallows, Chapter 33, The Prince's Tale}

Snape wouldn't be able to know about the Patronus-doe, as Harry never told anyone this detail (apart from the Trio). And if Snape was indeed the one that casted the Patronus while standing in the woods watching Harry, he would have captured him and handed him over to Voldemort, if he indeed was on the dark side.

The fact that he let him live while providing the primary weapon to destroy the Horcruxes -and hence, Voldemort himself- in my opinion is the ultimate proof that he was with the good side all along.

As to why Harry took the memories and gave Snape a last chance? It was probably a leap of faith, walking down the line into his forecoming death. He had, one way or another, already made up his mind about facing Voldemort, so what could Severus Snape do to him, while lying on the ground?

Answer 3

Firstly, the memories provided most of the missing pieces to show Harry a consistent and complete explanation for Dumbledore's and Snape's actions over all the years:

• Snape attempted to save Harry in the first-year from Quirrell's curse, knowing that Quirrell was up to no good, and Harry even chanced upon Snape asking Quirrell whose side he is on.
• Snape made Lupin's Wolfsbane potion correctly.
• Snape attempted to teach Harry occlumency correctly, even if his teaching methods were too harsh.
• Snape actually alerted the Order once Harry hinted to him that he saw Sirius in danger, despite pretending to spite Harry.
• Even after killing Dumbledore, Snape told Harry to keep his mind closed, which he would have no reason to if he was really on Voldemort's side.
• Snape sent the doe patronus to guide Harry to the real Gryffindor sword, and gave a fake one to Bellatrix to keep in Gringotts. (He did not know that Hufflepuff's cup was a horcrux of Voldemort, otherwise he might have done things differently for that too.)
• Snape tried to teach proper defence against dark arts, without any falsehood.
• Snape as headmaster tried to send students to Hagrid for detention instead of the Carrows.
• Snape did not injure any of the other Hogwarts teachers even when they attacked him to chase him out of the castle.

Secondly, Harry had seen tampered memories (of Slughorn) before, and he could tell that it was tampered. It is implied that memories are hard to fake. Also recall that Harry had checked with Lupin on the veracity of one of those memories (that he had snuck into while Snape was away, which made Snape not want to teach him anymore).

Thirdly, Dumbledore told Snape (according to his memory) that Voldemort accidentally put a bit of himself into Harry. He did not mention horcruxes, but Harry understood that it was somewhat like one. If Snape was truly on Voldemort's side, there would be absolutely no reason for Snape to give Harry any such ideas, much less a memory.

Answer 4

When Harry went to look at Snape’s memories in the Pensieve it was not a matter of trust, he just wanted something other than his own thoughts at a time when everything was so painful. Also, even Voldemort understood that Harry would come to him, rather than let everyone else he loved die for him. So even though Snape’s memories helped Harry see his path, they were not relied upon in isolation.