Harry snorted. "You're the one who told me I shouldn't have let Malfoy see that address, that there was no doubt he'd communicated it to 'all interested parties!'"
"There is no doubt," Snape snapped. "He did in fact tell his father your address. But since Lucius had long known it, that made no real difference to anyone. When I said you shouldn't have let Malfoy see your address, I was trying to make you realize how very foolish you had been! What if the letter had slipped out of its envelope and you'd handed Draco information the Dark Lord didn't yet have?"
Too Slytherin by half, Harry thought.
"When you were missing from school and no longer on Privet Drive," Snape continued, "that's when the Dark Lord took enough interest to have your uncle Legilimized and that idiot Lupin followed. What happened to you has got nothing to do with Draco!"
Harry's stomach sank somewhere down to the region of his knees as the truth sank in. "Um, so it's not his fault either that Uncle Vernon got killed?"
Snape just glared at him, his inky eyes coming clearer the longer Harry stared.
"All right, all right, so it's not his fault," Harry conceded, though he declined to feel too bad about the letter. Draco was a hate-filled little shite, and Harry was glad he'd had to hear that, and write it down in his own hand. Actually, it was sort of strange that he'd put up with that, assuming he had of course. Harry hadn't had a chance to check what the letter said. For all he knew, it was a list of people Draco wanted to hex. "I still don't trust him."
"That's your prerogative. Just consider this, Harry. The Dark Lord did not want your wand taken out of his reach. Therefore, either Draco was sincere when he stole it, or he was indulging some childish whim that he may or may not regret in future. If he was sincere, he deserves more from you than complete and utter scorn. If he was simply getting some petty vengeance against his father, then his recklessness has placed him in our sphere of influence. Shouldn't we try to influence him?"
"I don't know how you do it," Harry muttered, rubbing at his eyes. Funny, they hadn't been itchy before. Well, not like this. "Somehow you make be nice to Malfoy sound so sensible."
"Think about it," Snape merely advised. "Is there a problem with your eyes?"
Harry opened them again, and groaned. "Everything's gone dark again!"
"Lumos..." Harry sensed his teacher leaning closer, so close he felt a sweep of long hair against his shoulder. "Completely dark? Or not quite black, as you described before?"
"Not quite black." Harry flopped to his back as soon as Snape uttered Nox. "What went wrong?"
"Nothing. I told you it would take time. We'll dose you again with Elixir before I go."
"My vision's supposed to fade in and out like this?"
"Ideally, no, but your magical state is still indeterminate."
"You were going to tell me something about that wild magic," Harry reminded him.
"It takes a violent form because it's a manifestation of dark powers," Snape explained. "You've had them all along; you were the source of the black energy in the Dursley house."
Harry crossed his arms. "I'm not a dark wizard, Professor."
"I didn't imply you were. What you are is a normal wizard, although very powerful. Having dark powers doesn't mean you use them for ill. I have them myself."
"What does it mean, then?"
"There are nine primary classification systems in use, but the best definition, in my view, is this: you have the ability, should you wish to wield it, to control and harm other creatures, wizards included. You can utilize the power in other ways, perfectly acceptable ways. But what makes it dark is the potential for abuse."
Harry frowned, and rolled over on his side. "By that definition, all wizards have dark powers."
"To one degree or another, yes. You have more than most."
"Like Voldemort," Harry whispered, thinking of the prophecy. Marked his equal.
"But unlike him, you don't want to use your dark powers for evil. It's like your Parseltongue, Harry. You use it to chat with Sals. He uses it to possess Nagini."
"Or Occlumency," Harry murmured.
"Ah, Occlumency," Snape thoughtfully murmured. "On Samhain, you held off the Dark Lord, and even misdirected him into thinking I was still the bane of your existence. You credited me last night with saving you, but the truth is that in large measure, you were instrumental in your own rescue, Harry."
It wasn't a compliment, but Harry still felt praised, though he had to own, "Well, only 'cause you taught me how."
"I would say it was because you made the effort to learn," Snape corrected. "You practiced."
"Yeah," Harry said, wishing with all his heart that he'd have practiced when it would have mattered to Sirius.
Perhaps Snape sensed the direction of his thoughts, for he brought the conversation away from past regrets. "Occlumency is a dark power," he explained, "but it is not necessarily evil, as you demonstrated on Samhain. All dark powers, however, are very deep and strong."
"Okay, I get it," Harry announced. "Dark's not even that good a word. We ought to be calling them deep powers, or something. But what does it have to do with my wild magic?"
"After the operation, when you ran that high fever, your magical core was severely charred. It wasn't burned completely through, as Marjygold believed; the deepest of your deep powers remained. These are the hardest to bring under conscious control, which is why Occlumency is so difficult for most wizards. That you could acquire the talent so rapidly suggests that you were tapping into your dark powers."
"That's why I can't even tell when I'm speaking Parseltongue!" Harry exclaimed. "It's not really conscious.."
"And neither are your dreams. All dark powers," Snape confirmed. "And too, dark powers are what erupts as accidental magic. They did this when you were a child, Harry, though as you've undergone such traumas in the past few years, your capacity for rage has grown as well."
Harry thought about that for a while before he replied. "How do I get the accidental magic under control?"
"The usual way is through magical education, which teaches you to use light magic instead, to deal with this or that problem as it arises. Your capacity for light magic has been incinerated. It took some time for even your deep powers to grow back from the spark that was left, but they are present in full, now. Yet you still have no surface magic to calm them, which explains how when you grow enraged, your deep powers go completely wild."
"But how do I get my light magic, surface magic, back, then?"
Snape had let go of his hands a while earlier, but at that, he clasped them again. "I don't think you ever are going to get it back, Harry."
Harry just stared, seeing nothing, a choking feeling of utter panic coming up to cut off his air. He swallowed, but it was still there. It felt like the room was spinning, or like his head was floating up off his shoulders, or something---
"Breathe," Snape dryly recommended.
Harry tried, he really did, but a lead weight was pressing down on his lungs, constricting all movement. It hurt something fierce, almost like he'd taken a Bludger to the chest---
"Breathe," Snape said again, more stress on the word. "Breathe, you idiot child!"
He couldn't, though, not until a sharp blow between his shoulder blades startled him so completely that he gasped, then sucked in a huge wheezing rush of air to compensate. After Harry had gotten his wind back properly, which took a minute or two, he couldn't help but narrow his eyes, because damn it all, that blow had really hurt!