"That cat is very smart; it can understand me when I speak, and it can clearly express what it has seen."
"Before this, it tried countless times to catch Peter but never found the opportunity. Later, when Peter faked his death right in front of it and escaped from that boy, it told me everything and even helped me steal a note with the password to the Gryffindor Common Room, allowing me to go in and confirm it myself."
"A few days ago, I snuck into the Gryffindor Common Room again; Peter had indeed escaped. He is no longer by that boy's side."
Hearing Sirius's account, Sherlock frowned unconsciously.
"If Peter has escaped, will he still remain at Hogwarts?"
"He will! He definitely hasn't left!" Sirius said grimly. "Not only can that cat sense that he is still here, but given his personality, he wouldn't just run away."
"When I was in Azkaban, the other Death Eaters imprisoned there hated him to the bone, believing that it was the information he provided that caused Lord Voldemort to lose his power in the end, which led to their capture."
"Peter clearly knows this himself. With his timid personality, he would definitely leave himself a way out. If Lord Voldemort returns in the future, he can use Harry to secure his position. Harry is his other lifeline, and he won't let go of it so easily!"
Sirius's analysis made a great deal of sense, and Sherlock rubbed his chin thoughtfully.
"We could try the Marauder's Map. Previously, we hadn't considered the possibility that Peter was still in the Castle, so we didn't pay attention to whether his name appeared on the map. But if he is still in the Castle, we should definitely be able to find him on it. If he's not on the map, but we can confirm that Peter is still at Hogwarts..."
Sherlock turned his gaze back towards the Forbidden Forest, and Sirius and Lupin followed his line of sight.
"Then the place he is most likely hiding is still this forest," Lupin said gravely.
Sirius looked at them and asked, "The Marauder's Map? I remember that thing was confiscated by Filch a long time ago, wasn't it? Not long after we finally left school?"
Sherlock looked at Sirius.
"You had this map when you were at school?"
Lupin shook his head with a wry smile.
"Sorry, Sherlock, I haven't had time to tell you about this. The Marauder's Map was actually created by us. Back then, after Sirius and the others learned to become Animagi, Hogwarts Castle held no secrets for us. We explored all the secret passages, mapped them out, enchanted the parchment, and eventually it became the Marauder's Map."
Sherlock immediately understood.
"So the four creators shown on the map are the four of you: Moony, Padfoot, Prongs, and Wormtail."
Lupin then answered Sirius's question.
"The Marauder's Map later fell into the hands of those twins from the Weasley family, and then they gave it to Harry. A few days ago, Snape caught Harry using the map to sneak into Hogsmeade through a secret passage and discovered the names of its creators, so he called me over, and I took the opportunity to retrieve the Marauder's Map."
"Snape? He's also at Hogwarts?"
"He is the Head of Slytherin House and the Potions Professor."
Sirius clearly dismissed this with disdain. His attitude towards Snape hadn't changed at all with age, and unlike Lupin, he felt no remorse for what had happened back then.
"Well, now is not the time to talk about these things. We should return to the Castle immediately and use the Marauder's Map to see if we can find any trace of Peter," Lupin suggested.
Sirius looked hesitant. He didn't know if he could return to the Castle with Sherlock and the others.
Sherlock clearly noticed the problem and drew his wand.
"Change back into a dog first. I'll alter your appearance slightly so you won't be so conspicuous when you enter the Castle with us."
Sirius complied and transformed back into his large Black dog form.
Sherlock tapped him with his wand, making his fur fluffy and smooth, and changed its colour to a mixture of grey and white. Combined with his naturally fierce little eyes, he looked exactly like a different breed of dog.
"This way, you won't stand out as a Black dog. After we bring you into the Castle, we can claim that we brought you in to make it easier to track Black, because a dog's sense of smell is more sensitive."
Lupin praised Sherlock's brilliant idea.
"Perfect! Using Black to catch Black. No one will suspect that the dog currently tracking him is actually Black himself!"
With that, they took Sirius out of the Forbidden Forest and returned to the Castle.
It was just past six in the morning, and the Castle was still empty; no students would be awake this early.
Sherlock and the others went to Lupin's office first, then unfolded the Marauder's Map to search for Peter's name.
But after carefully examining the entire map, the three of them did not see the name Peter Pettigrew anywhere.
"Is it possible that Peter secretly found a way to erase his name from the map?" Sherlock suggested.
Lupin and Sirius—one man and one dog—both shook their heads.
"Impossible. No one can erase their own name from the map. Even if you put on an Invisibility Cloak, you would still appear on it."
Sherlock shrugged.
"I've erased my own name before."
Hearing this, Lupin and the others realised that, in the office they were currently standing in, only the names Sirius Black and Remus Lupin appeared. Sherlock himself was nowhere to be seen on the map.
Lupin looked at Sherlock in shock.
"How did you do that?"
"Actually, it only took two very simple spells."
Sherlock pulled out his wand and tapped the names of Lupin and Sirius Black on the Marauder's Map.
The next moment, it was as though an eraser had rubbed away their names bit by bit, and they suddenly disappeared from the map as well.
"The magic used to create this map is indeed ingenious, but the technique is a bit outdated. You only need to combine a Counter-Curse with an Erasure Spell to remove names from the map," Sherlock explained. "I discovered it by accident. I simply gave it a try, and it worked."
The spells Sherlock demonstrated were not difficult, and any reasonably competent Wizard could learn them. The difficult part was thinking to combine those two spells and apply them to the Marauder's Map, something most people would never consider.
"Even if it's possible to erase names from the Marauder's Map, it's unlikely Peter would think of doing it, and he may not even know that the map is in Harry's hands," Lupin guessed.
"If his name doesn't appear anywhere at Hogwarts, then, like Sirius before him, he's most likely hiding in the Forbidden Forest."
Sherlock rubbed his chin and asked thoughtfully,
"Should we tell Dumbledore about this? If he knows, finding Peter in the Forbidden Forest will undoubtedly be much easier."
Sirius suddenly changed back from his Animagus form. They had already agreed that he would remain in his animal form after entering the Castle, but Sherlock's question prompted him to return to his human form to voice his opinion.
"You cannot tell Dumbledore!" he said grimly.
Lupin and Sherlock exchanged glances.
Both of them leaned towards telling Dumbledore the truth. With his authority at Hogwarts and his influence over the Ministry of Magic, if Peter really was hiding in the Forbidden Forest, it would undoubtedly be much easier to find him.
"Why can't we tell Dumbledore?" Lupin asked.
Hatred flashed in Sirius's eyes.
"If Dumbledore learns the whole truth, then even if Peter is caught, he will hand him over to the Ministry of Magic!"
Lupin frowned at him.
"Wouldn't that be the perfect way to clear your name and ensure Peter receives the punishment he deserves?"
"It's not enough!" he shouted. "If the Ministry catches him, they'll only lock him up in Azkaban! Dementors are a torment worse than death for ordinary Wizards, but for someone who has mastered the Animagus transformation, they're no different from ordinary guards! Dementors feed on human emotions, but they ignore animals! That's also why I was able to survive in Azkaban for more than a decade without losing my mind!"
Sirius's eyes were bloodshot.
"I want to kill him! Kill him with my own hands!"
Sherlock sighed and waved a hand.
"You two decide. This matter is primarily between the four of you. If you decide not to tell Dumbledore the truth, I'll keep your secret."
Lupin looked at Sirius seriously.
"You need to think this through. If you ultimately decide not to hand Peter over to the Ministry of Magic, then your name can never be cleared! The Ministry won't even give you a chance to use Veritaserum. As soon as they catch you, they'll order a Dementor to administer the Kiss. If you want to survive, you're destined to spend the rest of your life living under an assumed name."
Sirius clenched his teeth so tightly that the muscles in his left cheek twitched.
"I've already thought it through! I was guilty to begin with! Even if I'm caught in the end, I'll accept it! But Peter must die!"
Lupin patted Sirius on the shoulder and sighed.
"I won't let them catch you. Since you've already made up your mind, I respect your decision."
Just as they were about to end their discussion, Sherlock suddenly interjected.
"But I want to remind you of one thing. Don't forget your godson, Harry. Perhaps you don't care about your own future, but he needs you far more than you realise."(TN: Exactly. Someone who actually thinks.)