Lupin pushed the door of the passageway so hard that it raised a huge cloud of dust.
He quickly stepped out of the secret path and into a messy, dusty house. The wallpaper had peeled off the wall, the floor was stained, a piece of furniture was broken, apparently by someone, and the windows were boarded up.
This was the screaming shack. Lupin and his friends had been here many times. Since Black had invaded the castle, it was very likely that he was hiding here.
Lupin sniffed the familiar scent in the air. He put his wand to his chest, cautiously crossing the dark hallway and climbed the stairs that were on the verge of collapse.
As on the second floor, everything on the second floor was covered with a thick layer of dust.
But this did not apply to the floor. Something had happened recently from here. It was a paw mark left by a canine.
Lupin looked down and was all too familiar with the pawprint. It was a mark left by Sirius Black. Black must have been here recently, and it was very likely that he remained hidden in the house.
Lupin gripped his wand tightly and looked carefully at the closed door at the end of the hallway. Black could be hiding behind the door, ready to make a run for it. Even if Sirius didn't have a wand, Lupin still felt he had to keep his guard up.
He approached slowly, trying not to make a sound, and focused all his attention on the tip of his wand which began to glow faintly.
"Come on Sirius, I know you're in there!" Lupin shouted outside the door, his voice echoing in the empty room.
Nothing happened; nothing could be heard but silence.
Lupin narrowed his eyes and in the next instant his wand sent a thick red light that blew the door open.
In the room, there was only a luxurious four-poster bed, and the curtains around the bed were full of dust. There was no one there, only he was standing in the doorway, panting.
Lupin dazedly dropped his wand. Black wasn't here. Perhaps he had been there, but had gone into hiding when he knew he had seen him this afternoon.
"Vile coward!" muttered Lupin under his breath.
Black's behavior did not meet Lupin's expectations. He was not a man who would run away.
He was the bravest among them when he was a student, but when he knelt and kissed Voldemort's robe, the courage of the past might have disappeared.
Now Black was no longer a brave Gryffindor, more like a sinister and cunning Slytherin.
Lupin stood for a minute in the doorway of the room and there was a bleakness clear on his face.
He sighed deeply and turned to leave. But he stopped immediately and saw that there was something on the bed. It was a picture.
Lupin walked over and picked up the photo.
There were four boys in the picture. From left to right, they were himself, James Potter, Sirius Black and Peter Pettigrew.
The four people in the photo were laughing very happily and waving at Lupin.
Lupin suddenly felt a little sad. He still remembered that this photo had been taken on the lawn in front of the castle gate when they graduated. Everyone received a memorial.
His own photograph had been sent by Hagrid for Harry the year before when he collected photos; James' piece was lost in the ruins the night he was attacked. Peter's piece should have been blown into fragments by Black along with his body.
The only one who still had this photo was Black himself.
It was possible that he had accidentally left it in the shrieking hut. Unexpectedly, Black was left with this photograph. Lupin thought he had already lost all sense of friendship.
Looking at this yellowed photo, Lupin's thoughts went back to the time when they had just graduated, the darkest era of magic.
At that time, dark wizards led by Voldemort were wreaking havoc in the magical world. They openly resorted to violence, spreading terror everywhere, killing dirty bloods and Muggles in the name of "fun," and even launching a wizarding war to change the magical world.
In that protracted war, Lupin witnessed the deaths of many people, including his former seniors, classmates, and many other good people.
The year they graduated was three years before the end of the war. They could not wait to join the Order of the Phoenix and be on the front line against Voldemort, although Voldemort and his Death Eaters had far more power than the Order of the Phoenix.
However, through close cooperation, they had repeatedly stopped Voldemort's plots and had escaped from his hands.
Lupin thought it would go on until Voldemort was defeated.
But in the last year of the war, everything changed. Dumbledore learned in advance that, for some reason, Voldemort was hunting James and Lily's son Harry. James originally intended to fight, but for Harry's sake, he finally listened to Dumbledore's proposal and went into hiding, protecting himself with the Fidelius charm.
Besides Dumbledore, he and Peter Pettigrew were the only ones who knew where James was.
James chose Sirius Black, who he once thought was his best friend and the strongest of all.
Lupin also naively believed that was the best choice.
But he was wrong.... They were all wrong!
Less than a week after Black became James and Lily's secret guardian, he sold them to Voldemort. Voldemort broke into their house that night. He killed them, but did not know why he had failed to kill Harry.
After learning this news, Lupin still remembered his reaction at the time. He was madly looking for Black. He needed to ask Black for the truth. Something must have gone wrong - why did James and Lily die and why did the Fidelius Charm fail?
Until that moment, he didn't believe Black would sell them to Voldemort.
Two days later, Lupin found Black.
But he was one step too late and Peter Pettigrew had found him before him.
When Lupin saw Black on that street, he was surrounded by Aurors. He'd torn Peter and the Muggles all over the street to pieces a minute before.
It was all clear. Black sold James and Lily to Voldemort. On further questioning, he admitted that he had killed Peter Pettigrew.
Lupin stood helplessly on the street corner. He saw Black laughing wildly there and as he wept silently in the corner. This was the only time he had shed tears since he was a boy when he vowed never to cry again.