Harry and the others find Voldemort talking to Snape.
Voldemort is quizzing Snape about the wand he stole from Dumbledore—the Elder Wand, that is.
Snape claims that the wand will definitely work for Voldemort and now "serves" him.
Voldemort is skeptical, though. He believes that since Snape killed Dumbledore, Snape will remain master of the wand as long as he is alive.
So, Voldemort slashes Snape's throat and orders the snake attack him.
When Voldemort and Nagini leave, Harry goes to see if he can help Snape.
He presses his hands to Snape's neck wound, and Snape demands that Harry take some of his tears.
Apparently, they'll allow him to view something in Dumbledore's Pensieve.
Then he asks Harry to look into his eyes, commenting that they are the same as Harry's mother's. He dies looking into those eyes.
Suddenly, Voldemort is doing that magical loudspeaker thing again and addressing everyone on the Hogwarts grounds.
He demands that Harry meet him in the Forbidden Forest, or he'll kill everyone who's been helping him. He's allowing for a brief cease-fire, though, so the combatants can bury their dead.
Harry and the others enter the castle and check out all the damage. And this is where the tears start, Shmoopers.
Fred Weasley is dead. As are Tonks and Lupin. Yeah, we know—we just can't.
Harry watches the mourners briefly, and he's clearly grief-stricken as well.
However, he has a job to do, so he moves on fairly quickly to Dumbledore's office, where the Pensieve is located.
He places Snape's tears in the bowl and dives into the memory Snape wanted him to see.
Basically, we're treated to a kind of megamix of Snape's memories.
First, we see young Lily (Harry's mom), Petunia (Lily's sister), and Snape. Petunia is calling Lily a freak because she can do magic, and Snape comforts her. Clearly, he wants to be friends with Lily.
Now the memory follows the kids to their first day at Hogwarts, where Lily is sorted into Gryffindor. Snape doesn't look pleased at that development.
Harry sees the romance between Lily and James Potter developing, and the fact that James is not super nice to Snape. He hears his own conversations with Snape in voiceover.
Ah, it's suddenly clear why he didn't like Harry from the start: He reminded Snape of James Potter.
Then we see Lily's death, and Snape grieving. Snape is mad at Dumbledore for not protecting her more effectively.
Dumbledore asks Snape to protect Harry, and Snape asks that no one ever know.
We also find out that Dumbledore was already dying before Snape killed him. Remember that cursed ring that ruined Dumbledore's hand in Harry Potter and the Half-Blood Prince?
Well, when Dumbledore came into contact with the ring, that was actually a death sentence—the curse on that ring would have eventually killed Dumbledore, if Snape hadn't.
Apparently, Dumbledore was aware that Voldemort had tasked Malfoy with killing him, and so he asked Snape do it instead at the proper time. After all, Dumbledore was dying anyway, and if Snape killed Dumbledore, he would totally earn Voldemort's trust.
So, yeah, there you have it, Shmoopers: Snape was loyal all along.
Thought that was the biggest reveal ever? Guess again.
The memory caps off with the biggest surprise of all: Dumbledore explains to Snape that Harry himself became a Horcrux when his mother was murdered. Wait, if Harry's a Horcrux, and Horcruxes have to be destroyed…does that mean? No, it can't...
Yup, you've guessed it: Harry has to die in order for Voldemort to be defeated.
In the memory, Dumbledore tells Snape that they must wait to tell Harry, but at the right time. When Voldemort is very weak, Harry must hear all this and must die in order for Voldemort to be killed.