This dungeon is my sanctuary. It's the only place that makes me feel like I am ten years old again, lying on the grass next to my best friend talking about the wondrous magical school named Hogwarts where we would remain as thick as thieves. Instead, that school drove an almost unyielding wedge between us. By some unspoken agreement, this year, our fifth, potions is the only class Lily and I sit together – only by a lucky coincidence; the tables in this room seat four. There are five Slytherin boys, and five Gryffindor girls in our year who all usually sit together, so, whilst we jumped at the chance to sit together, it wouldn't have happened if we were in any of the other dungeons. My friends hate her, her friends hate me, so outside of these four stone, windowless walls our interaction is minimal. But in this dungeon warmed by hot cauldrons, it's almost like we're not separated by blood purity and the inevitable war as we laugh and joke and talk like we used to. Well, we usually do.

Today, we're making the Draught of Peace, but the look on Lily's face is anything but peaceful as she reads over the instructions for what I guess is the fourth time. My potion, simmering away, is the exact purple detailed in the book. Lily's cauldron emits a green spark and she groans in frustration.

"Need any help?" I ask.

Keeping her eyes on her textbook, Lily shakes her head. "Do your own, and then let me drink it."

Amused, I turn back to my potion. As I add porcupine quills, I hear the laughter of Sirius Black. I don't need to know what they're talking about to know that they're laughing at me. They always are. Sure enough, moments later I hear Pettigrew say my name, too loudly for their hushed conversation. I glance at the table where my friends sit, but between their conversation and the complex potion, they haven't heard what I have. Neither has Lily, engrossed in powdered moonstone.

I wait until my potion turns turquoise (adding a few more quills than described gives better results) and leave it to simmer, before finally looking over to Black and his cronies. Meticulously, Black is adding powdered unicorn horn. A bit too much could have disastrous consequences. With a flick of my wand, the whole pot finds its way into Black's cauldron. Luckily for him the pot was almost empty and the resulting explosion only sets his robes on fire.

Blacks yelp gets Lily's attention and she whips round to the sight of Black with a few flames licking at the front of his robes. Really, it could've been worse. Wasting no time, Lily shouts "Aguamenti!" and directs the jet of water streaming out of her wand to Black's torso, then to Lupin's arm, which had also caught fire.

Eventually, Slughorn rushes over to their table. To my great pleasure, he reprimands Black on not reading the instructions properly. Brilliant, the professor's in a bad mood! He orders a sopping wet Black to the hospital wing to check for burns, even though his robes aren't even singed through. Lupin too, and Potter goes along for good measure. As they exit the dungeon, Black stares daggers at me, but there's absolutely no proof I did anything, so he doesn't accuse before the door shuts behind them. With just Pettigrew left, maybe I can get through this lesson with as little stress as possible.

"Pettigrew, clear up their cauldrons, there's only twenty minutes left," Slughorn snaps. "Anyone who doesn't have a passable potion by the end of the lesson will receive a detention."

The rest of the class turn quickly back to their potions. I turn to Lily, who bangs her head on the table hopelessly. I know for a fact she's never had a detention before, and I'll be damned if she's getting one today.

"At least it isn't sparking anymore." I say. No, her potion isn't sparking, but it looks rock solid.

Lily groans again and barely lifts her head to say "'Not sparking' doesn't class as 'passable'."

Inspecting the potion, I find it isn't as solid as it looks. "We can fix this. Just do exactly what I say."

After a quarter of an hour of me instructing Lily on how to stir her potion, how much hellebore to add and what temperature to simmer it, the draught emits a fine cloud of yellow smoke which, on closer inspection, smells slightly of rotten egg.

"Five minutes, then I'll check your concoctions." Slughorn says from the Ravenclaw table, where he's helping a stressing half-blood.

Eyeing her potion with distaste, Lily frowns. "That's it, my first detention. I'm starting to rebel. Next thing, I'll be smoking in the astronomy tower."

I roll my eyes and smile. "Stop being so melodramatic."

"I'm being serious."

I add the final ingredient, syrup of hellebore, to my cauldron and watch as it turns the required shade of silver.

"Here," I say and use my wand to switch the disaster in Lily's cauldron with the almost done potion in my own.

Lily gasps softly. Cheating is against her rules. "Sev, you can't do this!"

"Sure I can. Just stir it seven times clockwise and you're done."

Lily looks conflicted, and lifts her wand to switch them back.

"Ah, Severus, let's see if you've done it correctly." Slughorn booms from beside me. I start, and see Lily open her mouth, presumably to tell Slughorn of the switch. I give her a look that plainly tells her to just stir the bloody potion. She does.

Coughing slightly from the smell, Slughorn awards me with a detention. "I must say I am quite disappointed, boy. On Monday I expect a perfect Strengthening Solution."

"Yes sir."

Slughorn squeezes himself in between me and Lily, inspecting my – her potion. With the last stir, it emits a silver vapour; the sign of a perfectly brewed draught. "Aha! Perfect Miss Evans, as usual. Leave this here; I can give it to Madam Pomfrey to use. For that you don't have to hand in tonight's homework of a foot detailing the correct way to brew and administer a Draught of Peace," announcing the homework to the whole class now, Slughorn moves from between us. "Don't forget to include the effects of the potion and how it is used in today's society."

"I'll do the essay for you." Lily whispers as the rest of the class begin packing up their belongings.

"No, I'll do it. Don't worry about it." I assure her.

"Sev…" she starts.

I cut her off. "Slughorn knows our handwriting. He'd know if you did mine, then we'd both be in detention. Besides, it won't take me any time at all, given I actually do know how to make a perfect Draught of Peace."

Lily sighs. "Fine, but I'm going to read up on it too, in case it comes up in our OWLs."

"I wouldn't expect anything less."

The classroom is empty except the two of us. Pettigrew left last, laden with four bags left behind by his friends. I smiled to myself as I watched him struggle. It usually happens like this, one or both of us prolonging the time in here, as we know the next time we talk will be back in this room.

"I know you set Black's robe on fire, by the way."

This shocks me – and wipes the smile off my face. "Oh, er–"

"I'm not condoning it, but I heard them laughing at you, and Potter was saying the nastiest things. I'm quite upset, really, that his robes didn't go up in flames."

"You were still the first to extinguish them." I say, and then I want to take the almost accusing words back.

Lily swings her bag over her shoulder. "Yes, well I couldn't let them be seriously hurt." She looks me straight in the eyes. "You knew there was only a bit of the powdered horn in his pot, didn't you?"

I didn't, but I assure her that I did, anyway. No harm was done, so it doesn't matter now whether I wanted him to be seriously hurt or not.

Reassured, Lily walks across the empty dungeon to the door.

I pull a phial out of my bag. "Lily." I call as she reaches the door. Filling the phial with some of the perfect draught, I say, "This is for Monday, so I don't have to do your work for you."

Once I walk over to her, Lily takes the phial from my hand and smiles. "You're the best, Sev."

"What are friends for?" I ask, not looking her in the eye.

Lily doesn't reply. Instead, she lifts her chin up to plant a kiss on my cheek. Opening the door with one hand, she tucks the vial safely in her bag before going to join her friends who, as always, wait at the end of the corridor. For her, it's as easy as that to slip in to her usual life. And I stand alone in the dungeon with a searing hot cheek even as the air becomes cold with only the memory of burning cauldron fires.

A/N: So… My first Snily fic. I have no idea what prompted me to do this, it just came to me and demanded to be written, so here it is. Very different from my usual stuff, so I'd love to hear what you think!