No, it was the combined weight of all his past mistakes. His failures. He remembered them all with vivid clarity. Gellert, Ariana, Riddle, young mister Snape. And now, the latest tragedy to happen at Hogwarts. Minerva, Hagrid, all those poor, helpless students. The entire school in the hands of the Death Eaters. He felt responsible for every single death, even though it wasn't directly his fault. If only he had acted differently, if only...
He shrugged those thoughts off his mind as he waited for the door to open. He couldn't let his guilt have the better of him. He had to do as he had always done: use it as a motivation to go on and do better. There was still a chance to save Wizarding Britain from the evil of Lord Voldemort, after all. He had to do his best, even if he ended up fighting alone.
Finally the door opened. A moment of silence passed in which the man on the other side of it looked at Albus.
"Hello, Horace." he said, as Slughorn's eyes widened in recognition.
"Albus...I...damn, I haven't seen you in a while. Please, come in." Horace Slughorn moved his considerable girth aside and motioned for Albus to enter.
"I hope I'm not disturbing your evening, old friend." he said as he glanced around himself. It had been a while since he had come to visit Slughorn, but his house didn't seem to have changed much. Everything was as Albus remembered it.
Except for one little thing that he caught from the corner of his eye.
"Don't worry, Albus. I'm always glad to see you. Would you...would you like something to drink? Firewhiskey, perhaps? I have a bottle that an old student of mine gave me last Christmas..."
"No, thanks. I try to avoid strong beverages at this time of the day. If I could have a nice, warm tea, though..."
"Of course! Take a seat anywhere you want, I'll be back in a moment." Slughorn hurriedly left for another part of the house, and Albus sat on a big grey armchair in the living room. He then looked at the thing that had caught his attention.
It was a small trunk on a table in the living room, not far from where Albus was sitting. It was open, and there were a few objects slowly falling into it. A folded robe, a couple books, a hand mirror, an umbrella. Albus furrowed his brow as he watched.
Slughorn came back a moment later, carrying a tray with two steaming cups of tea. "Here. I was making some for me, so..." He noticed Albus looking at the trunk, and made a face as if he had just remembered something. He clenched his teeth as he put the tray on the table.
"Were you preparing for a voyage, Horace?" said Albus, and then took a sip of tea. Hmm...the warmth was fine, but, as always, Horace had put too much sugar in it. Oh, well. Might as well pretend to enjoy it. He drank the rest as the other man sat on a nearby armchair and took his own teacup.
"A v...ehm, yes. A voyage. I...I was going to visit a cousin of mine who lives in Ireland. I haven't seen her in a while, and...well, I figured it was a good chance to do it, since I...since I don't have much to do, these days." He drank his tea in one gulp and cleared his troath. "What about you, Albus? How have you been doing?"
"Quite fine, thanks for asking. I have been doing a few researches for an old project of mine, which brought me to the mainland. I have only just returned."
"Oh. I hope these...researches were fruitful, then."
"Indeed, they were." To be honest, he hadn't accomplished much, aside from convincing Nicolas and Perenelle to stay in France. The elderly couple had been considering moving to Britain, but as of now, things were too dangerous for them. Especially considering what Voldemort was really aiming for.
"Now, Horace. Let's come to the reason behind my presence in your home. As I'm sure you have realized, I didn't come here merely to visit an old friend and colleague."
"Ehm...actually..." Slughorn nervously twirled his mustache. At a nod from Albus, he continued. "So...to what do I owe the pleasure of your visit, old friend?" Albus didn't need to use Legilimency to realize that his sudden arrival was anything but a source of pleasure for Horace.
He sighed. Here comes the ugly part. "It's about what happened at Hogwarts."
Horace seemed to sink even more into his armchair.
"To be more accurate, it's about the Death Eaters and their leader, V..."
"NO!" Slughorn looked as if he had just stared at a Dementor's face. "No...please, don't say that name!"
"As you wish. I..."
"What do you want, Albus?" The other man now looked genuinely frightened.
Albus decided to get straight to the point. "I'm investigating on the past of...You-Know-Who. I'm trying to find something...anything...that could help us win this war. Back when he was a student, he was part of your little club. You spent a lot of time together. So I thought..."
"GET OUT OF HERE, NOW!" Horace had jumped from his seat and was now standing in front of Albus, fists clenched and eyes wide, face white as a sheet.
Albus didn't even flinch. "Just a few questions, Horace. Just a moment of your time. Then I'll be gone."
"NO! I won't...I don't know anything! Please, Albus, leave!"
"Not even..."
"LEAVE! NOW!"
Albus just sighed. He had hoped it wouldn't come to this. "Then, Horace, believe me when I say that I'm really sorry for what I'm about to do." He swiftly took out his wand as he stood up. "Immobulus." he said, aiming at the other man.
"What..." Slughorn barely had the time to open his mouth as he was hit by the spell. He became as still as a statue. Albus then stared into the other wizard's eyes, and let his mind do the rest.
Legilimency was a particularly complex kind of magic. Albus had a natural talent for it, and had honed this skill over the years, to the point that he could perform it effortlessly. He had never told anyone, but he had always been quite proud of himself for this.
What he wasn't proud of, though, was what he was doing right now. He didn't like...no, he hated having to immobilize Horace and look into his memories without his consent. And as much as he told himself that it was necessary, that there was no other way to learn something useful about Voldemort's past, the guilt hovered over him like a vulture over a carcass.
It's for a greater good, he told himself, regretting it a moment later. How much harm had those words led to? Was he becoming like Gellert? He tried not to think about it.
He was careful to stay away from those things that had nothing to do with what he was looking for. Through the memories, he went back in time and watched as Horace became younger. The 1960s, the 1950s, and then, the 1940s.
Wery well. Let's see...
He searched for anything pertaining Tom Riddle, anything that could give him a clue. The young boy that would later become Lord Voldemort featured in many of those memories. Albus saw him spending a lot of time in Slughorn's office, along with other boys and girls.
Hmm...not yet, but...wait a minute...
"Sir, I wanted to ask you something."
"Ask away, then, m'boy, ask away..."
"Sir, I wondered what you know about...about Horcruxes?"
Albus then watched as Horace hesitantly talked about Horcruxes and how they could be made.
So, this is how he learned about them. He first read about Horcruxes in the library at Hogwarts, and then asked Horace how they could be made.
Damn it, Horace! That's why you were trying to leave.
But Albus found he couldn't truly blame his old friend for this. He probably feared that Voldemort would try to recruit him, or worse, kill him so as to keep the Horcruxes a secret. Neither he blamed him for giving young Riddle such sensitive information. How could he have known his student's true intent? Riddle had been so good at hiding it. Just a curious, bright student asking something to his teacher.
He searched the rest of Slughorn's memories for what felt like an eternity. After reaching the Sorting Cerimony, he decided he had seen enough. The memories around him dissolved, and he was back to reality.
Wand still aimed at Horace, Albus pondered carefully on what to do next. He sighed. There was no other way. A flick of his wand, and then he spoke. "You will forget that I asked you about Voldemort's past. I came to visit you, and we just talked about what we have been doing since last time we met. You will remember that I left, and then you fell asleep on this very armchair. You will wake up in a few hours, and you will then resume what you were doing when I came." Another flick, and the Freezing Charm was undone. Slughorn fell on the armchair, eyes closed, and began to loudly snore.
Albus then left the house, his mind a whirlwind of thoughts.
He hadn't accomplished much. If only...if only he had found something in Horace's memories. Anything! He thought back to what he had seen. There had to be something, damn it! A detail he had missed...
Think, Albus. Think! The boy learned about the Horcruxes. He then proceeded to make one. At least one. Albus shuddered at that thought. Splicing a soul...the foul act needed to creat a Horcrux...
What else, aside from the locket? What else...wait!
He had suddenly remembered a small detail, something he had previously overlooked. In many of Horace's memories, Tom Riddle had a ring on his finger. He himself remembered seeing the boy with it, back at the school. He hadn't thought much of it, but now, knowing what he knew...Riddle wasn't the type prone to aesthetic eccentricities, so it had to be something of great importance. What if...
Albus decided this couldn't be overlooked. He had to learn more about Riddle's past. There was so much he still didn't know.
Tom Marvolo Riddle...how many secrets are you hiding?
Wait...Tom...Marvolo...what had Mrs Cole said? Tom for the boy's father...and Marvolo for her father...
Yes! Albus now had a hint. He knew where to look.
He Apparated away as soon as he thought that. He had a lot of things to do, a lot of places to visit, and he had to be as fast as he could.