a/n: wow people are actually here? That was one of the worst summaries ever. Apologies. So yeah this is one of the vvv few things the films did right.

disclaimer: really ok so I'm not Steve Kloves. And also I'm not JKR. You know the drill.

"Piss off."

The early July sunshine was filtering through the dungeon's windows, casting the room in a light green shadow. It flickered across Lily's face and James couldn't help but smile when he saw her, her features twisted into a pout of concentration.

He let the heavy door swing shut behind him and, whistling, made his way over to his girlfriend. At her words he chuckled and hopped up on the Potions workbench next to her. She let out a sound of exasperation and her fringe fluttered as she blew out an angry breath.

He smiled cheerfully at her. "Everything alright?"

"James," she whined, tearing her gaze from the shallow glass bowl in front of her to glare at him. "I hate you."

"Hate you too," he shot back. James nodded at the dish. "What're you're trying to do?"

"Here," she said, pointing at the lily petal floating on the top of the water. "I want it to sink to the bottom of the bowl and change into Francis, and -"

"Francis?"

"- yes, Francis the fish. Got a problem with that, Jim Jams?"

He poked her. "No."

"- and then it can do as fishes do all day. It's a present for Slughorn."

James chuckled and ruffled her hair affectionately. She swatted him away, smiling. "Why isn't it working?"

Glumly: "I don't know." Lily rested her chin in her palm, observing the bowl. "I know how to make it sink 'cause I just tried a simple Descending Charm which worked a treat, but when it hits the bottom...it needs to be a pre-meditated spontaneous Transformation."

James laughed, throwing his head back, and the loud sound filled the dungeon. "I think the universe just exploded."

"Shut up," giggled Lily. She looked at him. "It needs to appear spontaneous, then, while being completely timed to perfection. Changing the petal into a fish is the easy part."

James laughed again. "It's the good old piss on the floor, isn't it?"

"Piscifors, yes," she said, rolling her eyes but with a smirk tugging at her lips all the same. "Getting it to Transform at the right time is the problem."

James looked at the petal, then at Lily, who had a slight crease in her brow as she watched the bowl too.

"Well, it looks like you need someone who's wizard at Transfiguration, then, doesn't it, Evans?"

"Hm, wherever will I find such a person?" she said dryly.

"I reckon it needs a trigger of some kind," he said suddenly, pushing off from the workbench and walking around to the other side of the bowl. He squatted down so he was eye level with the water. "What about a Timer Charm? It might go off too soon, I s'pose..."

Lily knew it was best to let James ramble on when he was trying to work out a problem, so she twisted her hair up into a bun and pulled out a stool to sit on.

"What about," he slowly, "if you use a Contact Charm? Then it should Transfigure when it comes into contact with the glass."

"That could work," Lily said, nodding. "But it would need more of a formula than a simple incantation." She made a face. "I'd have to put in what it needs to come into contact with and how; what it should change to..."

"Yeah, but you can do it." He smiled at her. "We had to do something similar in the Charms N.E.W.T, anyway, right? And besides that, you're bloody brilliant."

Lily kissed him. "I know," she returned airily, attempting some semblance of their usual banter. She reckoned his casual - yet completely sincere - compliments would always set her world spinning slightly off-kilter. "Something like descendo tetigit latus piscifors, then?"

James grinned. "Something like that."

Picking up her wand and with a twinkle in her eye, Lily pointed it at the floating lily petal. Slowly she tilted the wand down, murmuring the incantation as she did so.

When she had finished, she stowed her wand back in the pocket of her robe and bit her lip. James looked on, a slow smile spreading over his face as the petal began to sink gracefully, dropping as if it was being blown through the air on a spring breeze rather than falling through water. When it hit the bottom of the bowl, the petal morphed into a small fish which began to swim around, a stream of bubbles following it and rising to the surface of the water.

"Francis!" Lily exclaimed.

James snorted and threw his arm around her shoulders. "You are not naming our children," he said solemnly, and she smacked him.

"What makes you think I'm having children with you?"

"My wit and incredible good looks," he said, bringing his hands up to cup her face and kissing her.

Lily kissed him back quickly then nudged his arms away, turning to pick up the glass bowl. "Was that one of your jokes?" she laughed as she placed the bowl down carefully on Professor Slughorn's desk. Lily squealed as he flung a ball of parchment at her. "Oi! You git, those were my notes!"

"Yeah, but you've done it now," James reminded her, wrapping his arms around her waist from behind as she repeated the charm which would turn Francis back into a petal until Slughorn arrived and saw his gift.

"Mm." She turned in his embrace and kissed him. "Come on. I know I've been doing this all morning -"

"Yeah, it took me ages to find you -"

"I mean, it's not like you have a magical map that tells you the precise location of each person in the castle, is it? Now that would be genius." Lily bent down and retrieved her satchel from under the workbench, gathering up the stray pieces of parchment and placing them inside. She slung the bag over her shoulder and held out her hand. "As I was saying, I know I've been here all morning but I wasn't planning on spending the whole day in the dungeons."

"I don't know," he said as she led him out. "The worktops don't look too uncomfortable, and we both know I'm not above shagging you in a deserted classroom. Where are we going?"

Lily shut the door to the Potions room and the latch fell into place with a click. She tugged his tie so he turned to her, and she kissed him, hot and heady. "As depraved as you are, I thought your bed would be a good place to start, Potter. I'm very grateful for your help and I want to thank you properly."

"You know what, Evans? Suddenly the Potions classroom doesn't seem quite so appealing after all."

a/n: according to the HP Wiki 'Ducklifors' is an incantation, and that's a mouthful if ever I heard one. Descendo tetigit latus piscifors roughly translates from mangled Latin into the instruction 'descend, and when you touch the side, transform into a fish'...or something along those lines. Reviews are like chocolate covered strawberries, and if I've used that before it's because they're that good.