A/N: I know from experience that short drabbles like these often spark longer fics. Should this happen to you while reading this, I'd love to read the resulting fic, so it'd be great if you could send me a message :) Other than that, feel free to write and publish anything my prompts inspired you to write.
calm
Simon was her rock in the stormy ocean. Isabelle exploded like a volcano at every emotion – desire, fury, indignation – but Simon stayed calm, so calm, like a deep clear mountain lake that nothing could upset.
grease
Short and greasy – that was how Isabelle's relationships used to be, with everyone. Lots of sex, little romance, no room for broken hearts. But with Simon it was different. Her relationship with Simon was careful, tender, the two of them moving gingerly around a gigantic heart of glass which they must keep from breaking.
champagne
The glass of golden champagne in Isabelle's hand looked as if it belonged there, Simon thought, of course it did. The purling liquid reminded him of her, sparkling and shining like a jewel between all the bottles of ordinary wine, prickly and spirited, hard to handle and easily overdosed. But the greatest similarity between Izzy and champagne in Simon's eyes was the prickly warmth that spread from his stomach to his fingertips and the dizzy light-headedness he felt when his lips touched either one.
offer
Originally Isabelle had intended her relationship with Simon to be like all the others, short and superficial. But the silly Downworldler had offered her so much more, love and comfort and patience, freely given without a second thought. And it was that, his unconditional and trusting display of all his heart for her to see, that caused the walls around her own heart to crumble.
chimpanzee
Before Isabelle had sometimes thought of Mundies as barely more than apes, living their lives ignorant of the world that really surrounded them. But now that she knew Simon she realized that they had their own intelligent way of looking at things, and that sometimes ignorance of one thing opens a new perspective on others.
mat
The mats on the floor of the gym in the Institute were supposed to prevent injuries when aspiring Shadowhunters practiced their fighting, but Simon and Isabelle discovered that they also helped to avoid bruises during an entirely different kind of exercise.
finger
In Isabelle's opinion, the part of Simon that had changed most with his transformation were his fingers, for where before they had only looked long and spidery, they were now elegant and slender, the pale skin so soft and cold that his touch felt like a cool spring breeze.
button
Izzy's red dress was reflected in the ivory buttons of Simon's tuxedo as he walked up to her and took her arm, leading her out of the stuffy dining room and out onto the terrace of the restaurant, where there was no one but the stars to watch them dance to their own music.
oar
Their love was like a boat on the ocean, a small wooden nutshell tossed about and subject to every whim of the water around it. But sometimes, either Simon or Isabelle would seize the oars in a rush of determination and bring their boat a few feet closer to its destination.
iPod
Sometimes, when Izzy had argued with her mother again, she would visit Simon, and they would do nothing but lie in bed together and listen to music from Simon's iPod, until her heartbeat had slowed down again and she started to feel guilty about the things she had said, which in turn was Simon's cue to provide her with enjoyable distraction.
wagon
They were sitting in the subway on their way home from a date when Isabelle noticed a couple opposite them just holding hands and looking happy; and the woman was pregnant. That was the moment she realized that she wanted what they had, that her time of sleeping around was over and that she was now ready for a proper relationship.
arch
As different as the two of them seemed to be, a nerdy vampire and a sultry Shadowhunter, their love was like a bridge that arched over the wide chasm between them.
legs
Isabelle's legs were a medical mystery, Simon decided. Long and slender they were, elegant and as feminine as was humanly possible, yet being a Shadowhunter's legs they were strong enough to rival a boy's.
doughnut
When Simon had first met her, he had expected Isabelle to be one of those girls you saw plenty of in high school – girls who spent their mornings fussing over their outfits and their lunchtime fussing over their diet. But Isabelle, to Simon's delight, glared at everyone who even dared to whisper the word 'salad' in her hearing, and didn't hesitate to tug in when Simon offered to buy her a doughnut.
mile
Sometimes Simon felt as if he was climbing a very steep mountain, with Isabelle's love waiting at the top. Mile after mile he set one foot in front of the other, hesitant and cautious, for the slightest misstep could result in his falling all the way back down again.
interlude
Sometimes, right in the middle of a particularly enthusiastic kiss, Simon would pull away from Isabelle and look at her, just to relish the fact that he was making out with the sexiest Shadowhunter on the planet.
choir
Neither Simon nor Isabelle had very good singing voices, but they didn't care about that when they were alone in Simon's apartment and they'd had a couple of shots, dancing through the kitchen to whatever was on the radio at the time.