When I was a student, Dumbledore warned me that my temper and exitability would be the death of me. Maybe it is, right now. As is my habit when working on dangerous potions, I warded the doors, but there is one person in Hogwarts for whom no door is warded. He walked in just as I was in the middle of the touchiest part of the reditus potion – the one with the three clockwise and two and a half counterclockwise stirs, while slowly drizzling the nematode extract in. I would rather blame the Headmaster for his distraction than blame myself for startling and dumping the whole vial in – especially now that I am covered in scalding potion. And I think what I'm hearing is my own screaming, but I feel oddly dissociated from myself; the room is darkening, my heart feels too big for my chest, I have no control over my limbs. The sensation of falling lasts far beyond what it should be for a simple fall to the floor. And just as I think that I'm falling into unconsciousness, my head hits the floor with a painful crack. I moan in an undignified manner as I put my fingers to the back of my head and feel for blood.

"What?"

I jerk upright and look to my left. The rooms feels like mine – it is the same shape as mine, the dank air and cool stone fells the same – but the décor is different. It's more brightly lit and warmer in color, and odd devices that are not mine are scattered throughout the room. And the man who just shouted – he is familiar. He is the Headmaster, as I remember him from when I was a student – no, he is younger still. Not a trace of grey shows in his short beard and tied-back hair. The casual shirt and trousers he is wearing hint at a much younger man underneath, and he springs from his seat with the vigor of youth. And drops his book with the carelessness of the same.

I sit up, wincing at the pain from my head. "Headmaster?" But I realize, even as I say it, that this is in no way the man I know as the Headmaster. Too much brass, not enough of the twinkle of cunning the Headmaster has in his eyes.

His eyes narrow. "No, I am Professor... a professor here. Who are you, and what are you doing in my chambers?" He advances on me warily, wand drawn.

I slowly start to stand. My wand is... not here. Where is here? My mind whirls – the reditus potion, memory restorer, allowing the mind to travel in the past. Of course – the addition of excess nematode extract might allow the body, as well, to travel in the past. And here I am, many years before these rooms became mine.

"There was a potion-making accident. I am the Potions Master of this school in the future; I..." the words catch in my throat as the Hea... as Albus grabs my collar, nearly strangling me, and pushes the wand into my temple.

"Don't play games with me. I know Dark Magic – it's a little hobby of mine – and you just reek of it. What is your mission? Who sent you? Don't play with me, boy!"

I almost snort. Boy? He looks younger than I am now. My patience, not a virtue I possess in great quantity, has gone. "I came from the future to teach you some manners..." I grab his hand to pull it away from my throat. With a muttered spell, he sends me spinning into the hard wooden desk that sits where my cauldron was... will be... I have no time to play with grammar. Panic is starting to swell in my belly as Albus grabs my wrists and leans his body weight over me. I don't have my wand – even an average wizard would have a distinct advantage over me in this situation. And even this young Albus is no average wizard.

And he knows it.

"I have something for you, boy." With a muttered Petrificus Totalus, he leaves me sprawled over the desk, arms back and legs wide, like a harlot waiting to be taken. I cannot look or talk, only scream inwardly, as I hear banging and clinking behind me. He weights me to the desk again, pinning my wrists with his body, and releases me from the spell with a word. One hand forces my jaw open, another pinches my nose. This younger Albus is physically strong, and I am forced to swallow what I recognize as Veritaserum. He steps back, and I gag on the last of the dose. I turn to face him, coughing.

"Sit." His tone brooks no argument as he points at the sofa that he vacated, covering me with his wand. I do. I feel the vague dissociation that means I am under the influence of the potion.

"What are you doing here?"

I have no control over my response. "Potions accident," I respond in the singsong voice of truth.

"Who are you?"

"The Potions Master at Hogwarts."

Albus crosses his arms, tapping his wand on the inside of his elbow. "Why do you smell of dark magic?"

"I am a Dark Wizard."

His eyes widen. "Is Hogwarts overrun by dark wizards in the future?"

"No. I am the only one. I betrayed the Dark Wizards; the Headmaster keeps me as a spy..." I trail off, but he waves the wand to indicate he wants me to keep speaking. To my horror, I can't stop. "I turned initially for selfish purposes; now I love the Headmaster, and could not go back."

Albus's eyes roll. "What idiot have they appointed as a Headmaster in the future?"

It doesn't matter if it's a rhetorical question; I have to answer it anyway. "You."

His jaw drops and his arms fall – and then he snaps his wand back at me. "Whatever game you're playing, boy..."

Once again, the room goes dark. Ah, yes, the ground lily petal that I added to the potion just before the nematode extract; that would ensure that the potion's effects would be limited in duration. Good thinking, Severus; every once in a while, you compensate for all of your bad thinking. I fall through blackness until I find myself lying on the cold stone floor, with the Headmaster looking at me with concerned blue eyes set in a wrinkled, white-bearded face. "Severus? Are you still with me, my boy?"

Boy. I struggle to speak, then I struggle not to speak... then I grab the hands on my shoulders, throw them aside, rise to my feet, and run, as fast as my feet will take me, away from that room.

Knowing that I only do it because he allows me to.