I squeeze my eyes shut as the knife slides across the soft flesh of my palm, but the coolness of the cave wall is oddly soothing to the oozing wound. Kreacher watches — or cringes, rather — beside me as I do so, his every word a plea to let him do this task and not myself.

But I ignore this and watch as a silver glow outlines the shape of a passageway and the rock within its bounds disappears. The gaping cavern that it reveals is magnificent in its own right, even by wandlight; I doubt that many have dared to tread in this place, even before the Dark Lord had decided to employ it. The ebony hue of the water, glassy and unfettered by movement, shines under the influence of my wand, the sole source of illumination save for a faint, greenish glow somewhere off the shores of the lake.

That Kreacher shudders and shakes at the sight of this place does not escape me. His account of the events that had occurred here only days ago starts to materialise in my imagination, but it doesn’t do to dwell upon such things. I have work to do. With that, a still horrified Kreacher leads me down the shore of this impossibly placid lake, and together, we retrieve the tiny boat he had described.

“Master Regulus mustn’t touch the water,” Kreacher warns. I do not know what is down there but decide not to find out. We board the boat and are soon being drawn across the expanse of the lake.

My blood begins to run cold as we near the centre. I can feel it in the air, the presence of the darkest of magic. I am no stranger to its aura, but the sorcery that had been set upon the object waiting for us is almost as black as the water below. And certainly, I have come to realise, it is blacker than I could ever be.

We reach our destination and disembark. I am immediately drawn to the glowing basin where the Horcrux is located, summoning attention unto itself like a mocking beacon. But I know its insidious secret. A demon’s heart in a well of nightmares awaits me, but I approach it willingly. From my pocket, I withdraw the locket that I had received upon my eighteenth birthday. In another lifetime, it would’ve been a token to the woman I would eventually marry, housing hopes and dreams and the flush of youth. But in this existence, its last act would be one of defiance.

Holding it out, I say to Kreacher, “Take this. When the basin is empty, switch the lockets. Take the other one and destroy it.” As I contemplate that second, diseased locket, my jaw clenches and I add, “No matter what, I want it destroyed.”

“Kreacher understands,” comes the throaty response. I spy the glint of tears on the old elf’s face, and it gives me a rush of affection for this dire-looking creature who I had stupidly offered up to the Dark Lord as a beast of inconsequence.

I see the water in the basin, but it is the most frightening of all. Kreacher had told me what it does; it made me sick and still does now. Silently, I wonder what it will conjure in my head, what sort of hells lurk in that crystalline fluid, but I push these thoughts away, as I will know soon enough. It is with resignation that I conjure the goblet that shall bring me to this enlightenment.

If I am anything, I am a fool, but there is no doubt within even the dimmest souls who know its contents that reaching the bottom of this basin will be the death of me. I can leave this locket here and never speak of it again. I do not have to perish for the sake of destroying the Dark Lord. A year ago, I would have found the concept laughable, but it is something Sirius of all people had said to me when we last spoke that has brought me to this place.

“You may be an idiot, but you’re my brother,” I repeat aloud to myself.

Sirius is many things: obnoxious, bull-headed, snide, and a blood-traitor. It is the last one that will make him a target, and the former three which will get him killed. As long as the Dark Lord lives and breathes, Sirius will forever be his enemy. I have seen both in battle and know with certainty which will win when that day comes.

Woodenly, I say, “Tell . . . tell no one of any of these events, Kreacher. Not my parents or my cousin or my —” I take a shuddering gasp and finish, “— my brother.”

“But what of Master Regulus?” sobs Kreacher.

“I will take care of myself,” I lie. “Do as I ask and you will have served me best of all.”

When Kreacher’s objections fade once more, I reconsider the basin. I see my eyes in its mirrored surface. Sirius has the same eyes, only without the burden of conscience. I envy him . . . not for the first time, but for the last. While I have finally found a cause worth dying for, he will have forever defeated me in finding a cause worth living for.

And, with that, I drink.