The next night, Saturday night, Harry took Ron to see the Mirror of Erised. Ron said he looked older, and he was Head Boy, as well as Captain of the Gryffindor Quidditch team. Ron's brother Bill had been Head Boy, and his brother Charlie had been a Quidditch Captain. Harry had the feeling that Ron's heart's desire was not really just to be Head Boy and Quidditch Captain, but also to not be outshone by his brothers all the time.

On Sunday, Harry's curiosity was getting the better of him, and he found Sirius at his teacher's quarters.

"Hello," said Sirius, opening the door. "What brings you here?"

"I had a question to ask you," said Harry. "If that's okay."

"Sure." Sirius sat down on the couch and beckoned for Harry to join him. "What is it?"

"I just wanted to know…" Harry sat down on the couch. "What do you see in the Mirror of Erised?"

"How d'you know about that?" Sirius asked in shock.

"It was in a book I read," Harry lied. "It shows not your face, but your heart's desire. So do you know what you see in it?"

"Well, not really," Sirius told him. "The last time I looked into a Mirror of Erised was before I went to Azkaban, and things were different then."

"So what did you see?"

"Well, what I saw was…" Sirius smiled sadly. "Do you want to hear another story about when you were a baby? The story of how I came upon the Mirror of Erised?"

"Yes, of course!" Harry nodded eagerly.

"Okay, well, I didn't know it at the time, but during the fall of 1980, when you were a few months old, Dumbledore was remodeling his house when he was at Hogwarts," Sirius began. "So he was running out of space for a few things, and he stored his Mirror of Erised in the Potters' cottage during the remodeling."

Harry thought now that it must have been the same Mirror of Erised that was in the school.

"So one night I was babysitting you when Lily and James were on a date night, and you wouldn't stop crying," Sirius continued. "I went to take you to a mirror, because babies like to look in mirrors—they think it's another baby they're looking at. Anyway, I came across the Mirror of Erised, but I thought at the time it was just a regular old mirror. Because you see, if you're completely content with your life, you'll see yourself exactly as you are when you look into the Mirror of Erised. And I was completely content with who I was, so staring back at me I saw myself, holding you in my arms, and you were laughing now, because you liked to look in the mirror."

"What did my parents see, do you know?" Harry asked.

"Well, the way I hear it, when Lily looked in the Mirror she saw herself with your aunt Petunia," Sirius said. "She always wanted them to be friends again like they were when they were younger. James used to look into the Mirror and see Lily, but once they started dating he started to see himself just as he was, too."

"I see all of my family in it," Harry told him. "My dead family."

"What?" Sirius looked around quickly at Harry. "When did you see a Mirror of Erised?"

"Uhh…" Harry realized what had slipped out and tried to think of a way to backpedal, but he couldn't.

"I thought you said you only read about it in a book!"

"Okay, fine, I didn't," Harry admitted. "Hermione and I actually found one in an unused classroom."

"Wow," said Sirius. "When?"

"On Valentine's Day," Harry told him. "We were having a midnight study date, but we heard Filch coming, so we ran for it and found ourselves in front of the Mirror. It's probably Dumbledore's Mirror of Erised, the same one you looked into eleven years ago."

"You know, you really shouldn't be wandering around at night like that," Sirius reprimanded Harry.

"Hello, kettle, this is pot," said Harry, pretending to talk on the phone. "You are black."

"Okay, I get the point," Sirius grumbled.

"Do you want to come see it?" Harry asked. "I'd like to know what you see in it."

"Well…all right," said Sirius. "But not after hours."

"Not a problem," Harry told him. "We can go now if you like."

…

The unused classroom looked less creepy in broad daylight. Sirius let Harry look in the Mirror before he looked himself. But Harry kept on looking and looking, like he had the past two nights, because he just couldn't get enough.

"Harry, do you want me to try it now?" Sirius said tentatively. "I mean…you have been looking for awhile now."

"Sure," said Harry vaguely, moving aside.

"Thanks." Sirius stepped in front of the Mirror—but then he froze.

"Well? What do you see?"

Sirius didn't exactly look right. He didn't take his eyes away from the Mirror.

"It's…it's the same thing I saw eleven years ago," he said slowly. "Except you and I look much older, the way we do now, and Lily and James are there, too. It's the four of us, just the four of us…"

"Your heart's desire," Harry said softly. "Your heart's desire is that my parents come back."

Sirius nodded and, with what looked like a tremendous effort, he looked away from himself and Harry's family.

"We shouldn't come back," he said shortly. "I shouldn't come back, and you shouldn't come back. This mirror is dangerous."

"Why?" Harry asked.

"It can drive you mad," Sirius told him. All of a sudden, he seemed to be in a big hurry to get away. "Listen, Harry, I mean it—I don't want you looking for this again. It's known to be addicting."

"Sirius, I know what this is about," Harry said, coming to a sudden realization. "Dr. Stefansen told you not to avoid things that remind you of your past, remember?"

"I don't care, I just want to go," Sirius snapped, pulling on Harry's hand. "Come on."

And with that, Harry allowed himself to be pulled from the room.

…

Harry didn't care what Sirius said. He was going back that night. This time, he didn't bring Ron, Hermione or Sirius along with him. He just went alone. Closer, closer he came to the unused classroom…he went to step inside…and…SMACK! Harry slammed into what felt like an invisible wall. Head spinning, he looked around; there was nothing there, but every time he tried to get into the room, he couldn't. Something invisible was blocking him. If only he could just get one glimpse…he strained his neck to look into the room and…

To his shock, there was Sirius, sitting on the floor in front of the mirror, knees drawn up to his chest, one hand touching the glass surface, as if by breaking it, he could reach what he saw. It looked like he'd been there for some time. His gray eyes were filled with the most terrible, empty longing. And the worst part was, Harry could see that his face was streaked with tears.

"James, Lily..." Sirius said hoarsely. "It's all my fault. I'm sorry...so, so sorry..."

And Harry watched as Sirius's thin hand lost its strength and slipped down, leaving foggy fingerprints on the glass. Sirius wrapped both hands around his knees, then, hugging himself as if he was cold. He buried his face in his knees and his shoulders shook. Harry tried and tried to get into the room, but now he understood. Sirius had magically blocked him. He could do nothing but watch his godfather cry, and then he knew, the Mirror of Erised really was dangerous. And it wasn't just dangerous. It was cruel. It got the heart wanting things it couldn't have.

Harry ran back to Gryffindor Tower as fast as his legs could carry him, knowing he would not come back again, ever, whether he was blocked or not.