When James had realised it was too late, he'd sent Snape upstairs to escort Lily and Harry to a safe place, but Lily had also refused to listen, and so Snape had tried to take Voldemort down from under cover. It hadn't worked, of course, but it was Snape who took Harry to Dumbledore, and Dumbledore had taken him back to Godric's Hollow so that Hagrid could "find" him.
Snape had tried his level best to save his parent's lives, his parents had ignored him, and instead of trying to escape with his own life, he defended them until the end.
How wrong...how utterly, incomprehensibly, wrong, Harry had been about Snape. All this time.
How wrong was he still, he wondered.
Resolved, he looked at his two friends for a few moments, who'd been watching in concerned silence as his face stormed through many emotions while he tried to work things out in his mind. "Do you two mind leaving me alone for just a few minutes?" Harry asked politely.
"Sure," Hermione said, standing, and levelling another glance at Dumbledore's portrait. The old wizard's eyes twinkled.
"C'mon, Ron," Hermione said, "we'll be just downstairs, Harry," she informed him, pulling the door shut securely behind her.
Harry looked at the portrait of Albus Dumbledore. "How did he know where the house was, if he wasn't the Secret Keeper?" In his tumultuous emotions, he neglected to clarify who "he" was.
No matter, Dumbledore knew.
"He overheard, who he thought was Sirius Black, telling Voldemort. He was hidden under the invisibility cloak and nobody knew he was eavesdropping on that meeting. Having heard the address directly from who we now know to be Peter's mouth, he Apparated directly there to try to warn your parents off."
"Why did Voldemort offer to spare my mum, then?" Harry wanted to know next.
"Severus insisted that the Sirius had asked for your mother as a reward for revealing your parents' whereabouts. Apparently, the impression was that your mother would find herself grateful to he who had asked for her, effectively sparing her life, and would thus willingly bind herself to him and be his wife."
"That's a lie! Sirius would never try to get between my mum and dad, or to take her away from him! He would never enslave my mother in such a way!" Harry yelled indignantly.
Dumbledore sighed in exasperation. "Harry. Once again, you are allowing your bad feeling about Severus, which you have earned, I might add, to colour your good judgement. What Sirius Black would or would not have done is immaterial. As we all know now, Sirius Black was neither a Death Eater OR the Secret Keeper, and thus was not in any position to ask Voldemort for her."
"Oh... right," Harry said, considering that for a moment. Then he suddenly looked up at Dumbledore's portrait and recoiled as if burned. "EW!"
"Hm. Indeed."
"Would Voldemort really have spared a Muggle-born as a prize, if a Pureblood had asked him to?"
Dumbledore regarded him with an odd expression. "I think I will have to defer to Severus' greater knowledge of Tom since he'd left school, but yes, Severus did seem to think that he would do so. I myself wouldn't find such behaviour terribly unusual. In fact, it's quite common behaviour for dictators and sociopaths. Remember, Tom himself had a habit of collecting trophies. However, Harry...Peter Pettigrew is not a Pureblood. Like your mother and Miss Granger, he is Muggle-born."
"WHAT?! I thought only pure-bloods could be Death Eaters?!"
"Now Harry, you know that is not true; you know full well Severus Snape is a half-blood."
"I...uh...well, yeah, I'd forgotten about that, but..."
"As is Tom himself. But yes, it is quite unusual for anyone to join a movement that advocates the wide-spread and painful death of what they themselves are."
"So who was the other Death Eater?"
"Well... knowing what I know now, I believe it was probably Peter Pettigrew. At the time, none of us knew who it was, since, at the time, of course, none of us knew Peter was a Death Eater, and the man in that scene is clearly not Sirius Black. But if you view the memory again, you see a small bit of hair that matches Peter's that comes untucked from the mask and cloak, and the man bends down to retrieve Tom's wand before disappearing. You yourself witnessed Pettigrew giving Tom his wand back. Initially, and understandably, I think the conclusion is that he Disapparated, but if you watch carefully, it could also be a transfiguration from human to animal. Again, none of us, at the time, knew that Peter was an Animagus, except Sirius Black, whom nobody was prepared to believe, and so he never even mentioned it. Remus Lupin knew, of course, but as the entire Wizarding World, including Remus, believed Sirius to be the Secret Keeper, and Peter to be dead, it appeared to be a moot point."
"I don't think Severus ever paused to consider that the rest of us were right about Sirius Black, because that would mean Peter Pettigrew had been a Death Eater. Severus never had any reason whatsoever to believe that a Muggle-born had joined the ranks until he saw Peter in the cemetery with the other Death Eaters after Voldemort's resurrection. By that point, of course, and in fact long before that, the damage to the relationship between Severus and Sirius, had already been done.
"Was Voldemort ever married?"
"An astute observation, Harry... you noticed that Voldemort appeared to have taken a ring off?"
"I did."
"Severus also caught that, although it took him several replays of the memory before he noticed it. Severus, however, knew that Voldemort traditionally wore a ring on his right hand, and was in a better position to describe it. Although to answer your question, no, I don't believe Tom ever married."
"Which ring did he take off?" Harry said, growing suspicious.
"That one," Dumbledore said, pointing to the table on which the Peverell heirloom ring lay.
"Let's move on. What was in that potion in the basin?" he demanded next.
"Hm. Well I am not actually the person to answer that, having not been the one that made it...but suffice it to say, it was, slowly and quite painfully, killing me. As was the curse on the ring."
Harry looked back and forth across Dumbledore's portrait, considering this, and crossed his arms and feet in thought as he leaned back in the chair. He tapped his right foot relentlessly. "Were you pleading for your life?" he asked next.
"I would never plead for my life, Harry...but especially not when a long and very assuredly painful and inevitable death awaited me, even if my dying wouldn't have assured my key spy's place in the movement."
"All right."
"Be careful, Harry...what you say, and what you do. It would be best if you not share this with anyone, I believe.
"I will be careful, and I won't tell anyone, not even Ron and Hermione," the younger man said. Pausing to reconsider, he said, "Well... at least, not anyone who doesn't already know," and with a determined look, swept from the office.
"Hermione, do you know anything about how to put only part of a memory into a Pensieve? So that nothing else can be observed?"
"No, but we can go to the library and find out..." she offered.
"Please, that would be very helpful. Ron...once we're done with that, can I borrow Pig?"
"Sure, mate."