The fastest to react was Sirius.
Although he had seemed largely uninterested in Meilia's matter, he understood that unless he helped Severus resolve this quickly, there would be no further information about Regulus.
Moreover, his current state made him more sensitive than usual. The moment smoke billowed and the sound came, he darted inside!
The place of fire and explosion was on the second floor. When they first arrived and found no one, Severus's group had performed a cursory inspection of the building. Following the smoke's direction, they quickly located the source: a fire in the second-floor bathroom.
It was clearly not a natural blaze. In an extremely short time, the magical fire serpent had reduced the entire bathroom to ashes.
By the time Severus and the others arrived, there was barely anything intact left. They could only try to extinguish the flames to prevent them from spreading and burning down the entire house.
"Someone's following us!" Lockhart exclaimed nervously.
Sirius was also on high alert, scanning the surroundings… he sensed something unusual in the air.
Severus stood in the center of the charred bathroom, wand in hand. The ashes around him, burnt beyond recognition, floated in the air.
Under the influence of magic, the debris and ashes clearly attempted to reassemble and repair themselves, but the damage was too severe. Even the most powerful Repairing Charm couldn't restore them.
Severus abandoned the attempt to repair the burnt items and instead began examining the bathroom, now nearly a ruin.
"That was the sound of Disapparation just now."
"Someone has indeed been following us. They clearly know what we're looking for and knew it was here."
Sirius was full of irritation.
"But this place is burnt to nothing! We have to catch that person!"
Severus, however, had already crouched down, wiping a handful of ash from the floor.
"Gilderoy, go to the Ministry, find Kingsley. Have him bring an expert in tracking Disapparation. It might be too late now. Since he was so confident about Disapparating right in front of us without hiding it, it means he's prepared, confident we can't track him... but we should still try."
Lockhart didn't hesitate, immediately Disapparating.
Sirius picked up where Severus left off.
"How brazen! All the Death Eaters in the Wizarding World have been rounded up now. Who would dare do this?!"
For such 'correct but obvious' statements from Sirius, Severus usually filtered them out automatically in his mind. He simply cleaned the dust from his hands, stroked his chin, and analyzed,
"This person knows what we're looking for and knew in advance we were coming here. But he shouldn't have been discovered by us. If he wanted to hide something, he didn't need to create such a big commotion. Wouldn't it have been better to just take the thing away quietly?"
Sirius was drawn in by Severus's words. He rarely used his brain, but that didn't mean he lacked one.
"Right! He had no need to do this, unless—"
"Unless there are two possibilities," Severus said softly. "First, he deliberately left clues for us, wanting us to chase him."
Hearing this, Sirius immediately shook his head vigorously.
"No one in the Wizarding World would dare do that now."
"Second, the person who destroyed this bathroom also didn't know exactly where the thing we're looking for, the thing he wanted to hide, was hidden. He only knew it was in this bathroom, so he simply burned the whole place down!"
Severus and Sirius exchanged glances. They both were certain this was the real answer.
"No Disapparation traces?"
Just then, Lockhart returned with the Ministry's Disapparation tracking expert. After a careful investigation, this expert surprisingly found no traces of Disapparation at all!
This result left Severus and the other two looking at each other in surprise.
"That's impossible," Lockhart was the first to speak. "One person might mishear, but the chance of three people all mishearing is too low!"
"It definitely was Disapparation!" Sirius also said. "No wizard could mistake that sound!"
Severus didn't reiterate the point. He simply looked at the Disapparation tracking expert.
The expert, however, shook his head.
"No. No one in the Wizarding World can completely erase Disapparation traces. Unless there's some unknown Transfiguration genius who has completely overturned and improved the spell."
Severus then narrowed his eyes as if struck by a thought.
"What if the one using Disapparation wasn't a person?"
His words initially didn't register with the others. It took three seconds before the expert was the first to comprehend.
"You're right! Disapparation isn't exclusive to wizards! Besides wizards, other creatures can use magic similar in form but fundamentally different in structure from wizards'!"
"I've encountered a similar case at the Ministry. It involved a goblin thief..."
The expert launched into a lengthy explanation, but Severus and the other two had already huddled together. It didn't take much brainpower for them to guess the most likely answer.
"It's a house-elf!" Sirius said with certainty. "Just like Kreacher described to me, house-elves can use Disapparation even under the Dark Lord's restrictions. They can also evade wizard tracking!"
"House-elves only obey wizards' orders," Lockhart followed up urgently. "The mastermind behind this is still a wizard!"
Severus, however, shook his head.
"That's not necessarily true. Don't forget, after the Fawley house was completely abandoned, their house-elves were also freed."