At two minutes to ten, Potter shuffled into the sitting room. Snape hid his surprise, but he couldn't remember Potter ever being on time for anything, much less early.
"I see you have learned to read a clock, Mr. Potter. Congratulations." Potter gave no indication he had even heard him.
"I'm ready whenever you are, sir."
"Very well—Legillimens," Snape said, his wand raised. He saw flashes of several of Potter's memories. Many he had seen before, a few he had not. He saw a fat boy running after a young Potter with a baseball bat, Potter and Chang standing very close and leaning closer, Mr. Diggory falling to the ground and a flash of green light, Sirius Black falling through the veil of death at the ministry and Potter screaming after him with all his soul—he heard a sob and his concentration faltered.
"There you are, Mr. Potter, simply startle the Dark Lord out of your mind by breaking down and crying. I'm sure that will do the trick." He expected Potter to get angry, to yell and scream as he was wont to do, but he just stayed where he was. He had fallen to his knees at some point during the spell and knelt there, looking at the ground.
Slowly, he raised his head. "Maybe we shouldn't do this, professor."
"Why ever not, Mr. Potter? It was your request."
"It's just that…I just…I don't want to have to think about that anymore. I get enough of it in my nightmares," Potter said quietly and gave a small shudder.
"If you learned to close your mind, I could not force you to think about things you do not wish to think about." Snape paused. "I thought you said you were no longer having the nightmares?"
"Not Voldem—Sorry, Professor. Not Dark Lord-induced ones. But I still have nightmares every night. Why can't bad things just be over once they're over?" The boy seemed to trail off, talking to himself.
"You must learn to occlude your mind. It is imperative."
"But I don't know how!" he said, looking somewhat desperate. "I don't know what I'm supposed to do. I try to imagine that I have a big wall around the memories I don't want you to see, but it just seems to draw you there faster. I don't know what else to do!"
Snape silently chastised himself as he realized Potter was going about this all wrong, and it was at least partially his fault for never having told him how to go about it properly.
"Sometimes walls can be useful, if they are strong enough—very strong. But, as you said, walls will indicate to an intruder that you are hiding something. Do not focus on trying to hide memories you wish to keep private. Instead, focus only on those remaining, focus on the image of yourself you wish to project. Create a persona for yourself that gives your enemy no tools with which to torment you."
Potter was looking at him with wide eyes. "Wow, I can't believe it. That actually made sense!" he said with a sheepish smile.
"We shall begin again. Prepare yourself—Legillimens." This time, Snape saw a different set of memories. They felt forced, and he attempted to push past them. He saw Potter flying high above the Quidditch pitch, studying at the library, eating in the Great Hall with Ms. Granger and Mr. Weasley…and then he felt something give…and he saw Vernon Dursley's fist flying toward Potter, Bellatrix Lestrange cursing Black before he falls through the veil. He voluntarily pulled out of Potter's mind.
The boy was back on his knees, shaking a little. Snape almost pitied him.
"That concludes our lesson for the day. You seem to have successfully grasped the concept I was trying to impart to you. However, it will require much practice before it will feel natural to someone attempting to invade your mind."
Potter was giving him a very odd look, and he realized he'd actually complimented the little brat.
"Erm, thanks, Professor." Snape did not reply.
He conjured a cup of tea for himself and Potter and they sat on opposite sofas, quietly sipping. When it seemed Potter had recovered sufficiently, Snape attempted to satisfy his curiosity.
"So why is it that you find yourself unable to remain and your aunt and uncle's? Have they forbidden you to autograph your fan mail?"
Potter looked up sharply. "I don't really wanna talk about it, sir." He quickly squeezed his eyes closed and turned his head to the side.
"Relax, Mr. Potter. I will not attempt to break into your mind without consent simply to satisfy my curiosity."
Potter turned back to him and cocked his head to the side. "Really?" He seemed genuinely surprised.
"Of course not."
The boy looked quite relieved to hear it and visibly relaxed.
After a moment, he asked, "Did you learn to be such a good occlumens because you had to to spy for the Order, or were you already good at it?"
"Do not expect that I will answer your inquiries when you do not answer mine. Conversation must be reciprocal."
A faint blush crept up to Potter's cheeks. "Yeah, yeah I know. It's just…you know. Do you think we could start…smaller?"
Snape tensed a bit, though not visibly. "Certainly."