Regulus Black the Potions Master

Chapter 4

The end of his first year as a teacher came faster than he expected, in a whirlwind of revisions, exams, and nervous breakdowns. A girl barricaded herself in his dorm, unceremoniously throwing out her roommates, for three full days before he was forced to break in and appease them. He learned to have a box of tissues always full and ready in his office for any student who was sniffling. McGonagall even gave him a sympathetic nod of understanding when he rushed into a staff meeting ten minutes late, looking tremendously overwhelmed.

And then finally the school year was over and summer came. And within hours the school is empty and quieter than Regulus has ever seen it.

The summer was very fruitful in his endeavor alongside Dumbledore, he could have done more had it not been for his current seat in the Ministry thanks to his title as Head of House Black.

Between the death of his mother in early 1982 and the start of his work as a teacher in the same year, Regulus was not much in his childhood home, still preferring his small cottage in the village where he stayed to recuperate; but during that vacation he decided his house needed a real cleaning. Not only the normal filth, he fully trusts Kreacher to keep the house perfectly tidy, but Grimmauld Place is home to a lot of dark magic, which is not surprising with all his family's ideology. And even after the war, there are still dangerous things in that house.

So he spent nearly the entire first month researching every protective and containment spell he could and turned the basement into a magical vault where he dumped all the evil stuff he didn't want to fall into the wrong hands.

It's not that he didn't particularly believe in the ministry's suitability, it's just that he doesn't. Not after Nott and Malfoy managed to get away with their war crimes with only the flimsy excuse of being cursed with the Imperius.

No, those objects and books better stay with Regulus where no one tries to use them for something dangerous and stupid, like trying to bring Voldemort back from wherever he is.

Speaking of his possessions, he went to Gringotts to sort out some things and visit the Blacks' vault there would be dark magic things with the money, he had no doubt when he entered the vault. But the shiver he felt wasn't just a fluke.

Regulus could freely say that he was used to the Dark Arts, he is a Black; he can even admit how familiar he is with the Unforgivable Curses themselves, having been on both sides of at least one of them. Now that uncomfortable shiver that makes his Inferi scars burn, that he only felt one other time, with a locket; Slytherin's Locket which was turned into a Horcrux.

The theory that the Dark Lord had made more than one Horcrux was at best a nightmare and at worst a terrible reality. So when he was drawn to a specific object among the many golden goblets on a shelf.

The same feeling he felt when he found the Medallion, the dark magic oozing from the small cup as if it were oozing from the object.

Taking the cup with him back to Hogwarts, the only place where he could find Dumbledore, Regulus presented him with the object.

"How did you find him as a child?" Dumbledore asked.

Regulus was willing to ignore the old man calling him a child, watching him cast detection spells on the cup. He spent the drive to Hogwarts torn between hoping he was wrong and the cup just had some curse on it, and wondering if it was a Horcrux, how in Merlin's name did it end up in the Black Vault?

Considering that hypothetically it was a Horcrux. It is assumed that the Dark Lord has more than one, but the Locket was overprotected, beyond natural barriers, Voldemort hid the locket in this cave with various magical enchantments to guard it. First, in the cave, one could not Apparate and Disapparate; second, an unmarked door that could only be opened by paying blood on the cave walls; third, an Inferi-infested lake; fourth, an invisible rowboat that transports only one wizard at a time safely across the lake; fifth, a stone basin filled with a green potion that could not be disappeared, transfigured, or otherwise altered to change its properties.