I wait for a week before I lay my trap.

We go sledging in the fields round the back of the house, build a ten-foot snowman. Toast marshmallows and sit by the fire in the lounge. Talk and read and laugh. Play Scrabble and charades and Cluedo.

I always win at Cluedo because I'm the better leglimens. Try as he might, Tom cannot hide his cards from me.

Needless to say, it's the best holiday I've had in a while. So I procrastinate on telling Tom the truth, because I don't want things to be different between us.

There's no way this kind of bombshell won't change everything. It frightens me more than I would like. But after a week, I know that I can't keep avoiding it. Not if I want to live.

I have an old pensieve at the house. It's from the sixteenth century, a repurposed baptismal font that I rescued from a doomed monastery. The magic of the house has preserved it immaculately, so that its glistening white marble has not weathered or crumbled with age, and the intricate carvings gouged into its exterior are intact. There is a shining copper basin within the font, brimming with a silvery liquid, like molten pewter or swirling mist.

The pensieve lives in a cramped study, commanding the attention of the towering bookcases that congregate around its glow. It's not a room that Tom would have any cause to go into, but that is easily amended.

"I need Tom to find his way here tonight," I say, out loud, to the house, as I set the scene for Tom's arrival. It feels oddly underhand, arranging the font and the room in order to entice Tom in. Like I'm part of some twisted game of Cluedo, and Tom will walk in and say "It was Salazar, in the Study, with the Pensieve!"

I nearly laugh, out of sporadic, nervous amusement.

The house doesn't immediately reply to my request, and I pause, waiting. Then a random book falls without reason from one of the bookshelves. It's as good an acquiescence as any.

I leave the wooden lid off the pensieve, so that its shimmering glow remains undimmed. The memories- my memories- are already inside. I ensure that the door remains wide open as I leave, the silvery light spilling into the hallway, and the trap is set.

It is half past one in the morning before Tom finds the pensieve. Presumably awoken from his sleep by the house's magic, he wanders restlessly along the labyrinthine corridors, unwittingly drawn towards the study. I follow him, noiseless and invisible.

He pauses at the sight of the open door, and the light seeping out into the corridor that is otherwise shrouded in darkness. Curiosity overrules what is perhaps better judgment, and he cautiously steps into the study, oblivious to the fact that I am only a few paces behind.

When he sees the font, he knows exactly what it is immediately. He caresses his long fingers reverently over the white marble, gazing down into the swirling liquid with unrestrained wonder. The radiance of the metallic fluid laps gently over the harsh, angular panes of his face, making his skin bone-white. I clench my wand tightly, wanting him to hurry up and find out and yet simultaneously wondering if it's too late to knock him out, wipe his memory and send him back to bed. My sense of self preservation prevails, however, and as he lowers his head to the bowl, I point my wand directly at his back and think: leglimens.

It's a horrible breach of Tom's privacy, I know, but it's not as if this is the first time. And plus, it's necessary. This way I can see unseen.

Tom's mind envelops me, and his thoughts wash over me until they become my thoughts and I become him and he becomes me and there is no boundary between out two minds because I've gone deeper into his skull than I ever have before. What he sees I see, and what he feels I feel. He is in control, but he doesn't know that I am there, his shadow, inside his head.

I open my eyes. The vague sensation of falling has faded, and I'm standing in a dim, mossy cave in a forest. There is a greenish, flicking light coming from the cave's throat, and I descend deeper into its maw. Offhandedly, I wonder whose memories these are. Probably Evangeline's, although it seems out of character for her to leave them carelessly out in the open for anyone to stumble across. But if not hers, who else's? After all, I'm the only company she tends to keep. And I like it that way; I think she does too. She's the only person I've ever met who's looked at me and not been afraid, and it makes a nice change. A change I never knew I needed until she was suddenly just there, berating me and laughing with me and matching me in every way. An equal, finally.

It's been good, if strange, not having that cold emptiness, that void inside. Pain and hate never did quite fill it, but she did. Maybe I'm not just there yet, but I think I could be close. Who knew that was what friendship could do? It sort of makes sense now, why other people have friends. I never understood it before.

The greenish light dancing off the cave walls brightens, and I round the corner and see a small, emerald fire, the flames crackling and leaping without wood. Seated cross-legged by the fire is a boy. He's about thirteen or fourteen, with dirty, pallid skin and dark hair. I know enough about memories not to bother talking to him, so I stand and watch. He leans forward intently, his outstretched hand lovingly stroking something I cannot see, and murmuring reassuringly to it. I step a little closer, and the sickly light falls on a beautiful, coiled snake. The boy pets it adoringly, his chapped lips whispering softly. At first, it sounds like unintelligible sighs, but upon listening intently, I realise with a jolt of shock that the boy is hissing. Or, more precisely, speaking Parseltongue.

"It's okay," he croons tenderly. "It's all going to be alright."

I stand frozen, drinking the words in greedily like one gulping water in a desert. I've never heard another human being speaking Parseltongue, never met another Parselmouth. Except for my uncle, but he was an idiot and doesn't count.

Then I take a proper look at the snake, only it isn't a snake because I've seen my fair share of snakes and I know one when I see it. No, this serpent is different: thicker, with rows of spiked frills running along its length and framing its head. And its eyes, too young to kill, are a fierce, vibrant orange. A sudden realisation dawns on me, horrible and exhilarating and utterly insane.

The serpent, although young and small- less than a metre long- is unmistakably a basilisk. And there haven't been wild basilisks- or any basilisks, for that matter- recorded in Britain for the last five hundred years. Except for the one I suspect is in the Chamber of Secrets. Not that its ever shown its face to me.

I look back to the boy, because something about his face is familiar, and I know I've seen him somewhere before. But before I can begin to put the fragments together, the scene around me dissolves and I am somewhere else entirely.

There is a gushing river. It tumbles down a series of rapids, framed by great slabs of rock on each bank. The sun is out, and the rock is smooth and warm to the touch. I can barely hear anything over the guttural roar of that pounding water, churning over the well-rounded stones of the riverbed.

The boy is here, too. Perhaps a year or two older: he is several inches taller and his eyes are sharper. Sixteen, perhaps? He appears less impoverished this time; gone is the dirt from his face, and his skin has some more colour, although he is still pale. There is something else different too, a kind of gravitas that wasn't there before. He's more poised, more at one with his surroundings. But, I note, he's still very thin. Unhealthily so. It shows up in the way his eyes are slightly sunken, in the malnourished prominence of his cheekbones.

The basilisk is draped lazily across his shoulders, and he whittles away at some wood with a small silver knife.

A wand, I realise. He's making a wand.

The face is so achingly familiar, and yet I can't quite place it. Perhaps a distant relative of mine, if he can speak Parseltongue. But then how is it that Evangeline has his memories in her pensieve?

Then I'm back in a forest. Maybe the same one as before. The boy is a little older yet again, perhaps eighteen. It's hard to tell, with his lanky frame and gaunt face. He's sat in a tree, high up and well-concealed, casually levitating twigs with his wand. There's a sudden sound of hoofbeats from below and his concentration breaks; the twigs fall. He looks down in mild curiosity to see a small group of young men, all in armour, all on horseback. They wear varying colours of cloaks, embroidered with their family emblems. The leader of this little cadre is a well-built, blond young man in a deep, crimson cape. There is a large, ornate silver sword at his hip, set with fat, glittering rubies.

My breath catches. Catches, because I know that sword. Just like I know the lion crest stitched onto his cloak.

This can't be happening. These memories… they can't be real.

The group is clearly a hunting party, a little posse of nobles' sons. They pause, and signal to one another silently. Then they all branch out in different directions.

Godric Gryffindor heads slowly back the way they came, directly under the tree where the boy perches. He draws his sword quietly, looking around for potential prey.

He doesn't realise that he has become the prey.

I spot them, and the boy, from his vantage point, spots them too. Bandits, or outlaws, or whoever they are. It doesn't matter. All that matters it that it's an ambush, and Godric doesn't even see the arrow that's fired directly at his head until it's too late.

Salazar sees it, though. Salazar, because that's who he has to be if this is Godric Gryffindor.

The resemblance to the portrait is uncanny.

With a flick of his wand, Salazar stops the arrow mid-flight. Godric's head whips around and he stares at it, suspended in the air an inch from his head. Then more arrows come, and Salazar stops them all, and they clatter to the ground, harmless. And Salazar leaps down from his tree, wand raised, and Godric can only stare in shock as Salazar proceeds to obliterate the bandits that come charging through the trees. It's over before it's really begun. I can't tell if they're dead or just unconscious, but either way, I don't particularly care.

A tiny smile appears on Salazar's lips as he surveys the destruction he has just wrought.

Godric dismounts, and approaches Salazar. Salazar turns to face him warily. Godric pulls his helmet off.

They're so different, I think. Godric is tall, broad and muscled, with fair hair and a kind of chivalric handsomeness. He can't be much different in age than Salazar, but in physicality he seems years older. What Salazar lacks in frame, however, he more than makes up for in presence. Although wiry and malnourished, there is that underlying sense of age, power and wisdom in him. His dark eyes look as if they've seen the rise and fall of kingdoms.

Slowly, Godric draws his own wand. Not as a weapon, but as a gesture of trust. Because simply carrying a wand must've been enough to get you burnt alive at this point.

Salazar stares at him.

"You're one of us," Godric says, quietly.

Salazar nods.

This is my ancestor, I think. This is the story of my blood.

The scene changes again.