A/N: ... I don't have an explanation. I apologise to all biology students and those who work in the field of biology. I seriously do.

Warnings: uh, innuendos, mature themes, Alfred's a dick and he's bored, and he's horny. BAD BIOLOGY PUNS. You've been warned. I hope you enjoy!

Alfred's desk had long since been cleared of finished cosmology assignments, his bag packed three times over for the next day, his and Ivan's shared student apartment's cupboard raided multiple times, and now he had settled onto their bed. He'd tried doing some studying, but he'd soon gotten bored of the text he had already read twice, despite the first being more than enough for him. He'd then shifted to Ivan's bedside book, but realising he'd read it already and remembered the plot to the word, he soon felt bored of it, too.

Now, he'd been reduced to idle texting and surfing on his phone. Matthew wasn't the greatest company, especially not when he was attending a party with his foreign boyfriend. Alfred hadn't bothered on the basis that "It's halfway across the campus for all the nerds in Medicine!"

He regretted ever calling medical students 'nerds', because they did throw parties where punch was spiked with copious amounts of almost pure ethanol. Alfred hadn't honestly thought he would end up watching almost an hour's worth of Matthew's Snapchats of Gilbert drinking and singing. Matthew was shouting encouragingly in the background.

He had honestly thought - hoped - his Sunday evening would have ended up differently.

Instead, Ivan's professor had decided to pull a major dick move on Friday, and set a quiz for the Monday immediately after. And the professor was notoriously known not only among students of Biological Sciences or Biochemistry but across the entire student body to be one with unbelievably harsh marking and an extreme distaste for those who ever even once dared get below a pass on any one small exam.

Ivan was going for a Masters in Biological Science and wanted to carry on to a PhD, though, and the professor was notoriously good at making students' life hell. And Ivan had an impeccable track record to keep clean. And he had decided that, come hell or high water, he would make that teacher like him - which was why he had now spent the entirety of the weekend hunched over his books and checking through lab reports and molecular biology notes, and Alfred had already peeked over his shoulder enough times to know that proteins were his main focus. Alfred himself had never really cared for biology even in high school, so he didn't bother reading much more about Ivan's studies.

Alfred glanced at the clock. It had been a minute and seven seconds since he'd last checked it. His eyes settled on Ivan's back. Alfred was most definitely bored, and he had been neglected the entire weekend, and it was already way past Ivan's time for a study break. He needed attention.

Bored Alfred also meant horny Alfred.

Alfred put down his phone and stood from the bed, before ruffling his hair nicely and striding over to the desk where his boyfriend was hunched over, scribbling furiously away at some last-minute notes. He planted his hands on the back of Ivan's chair.

"Ivan, how long you gonna be there?"

"M-hm."

"Yeah, no, how long, as in time-wise?" Alfred tried again.

"Yes, yes, I know, I will be done soon."

Alfred sighed. "Babe, buy your book dinner before you decide to make love to it, too."

Ivan finally turned to Alfred. "What?"

"Oh look," Alfred smiled. "He's alive!"

"I am sorry, Alfred, but I do need to study."

"You know the stuff already!"

"Just an hour, and then I'm all yours." Ivan settled back over his papers, and Alfred was once again ignored. Ivan was sometimes too studious for his own good.

Alfred debated for a minute, before he placed his hands on Ivan's shoulders, and smoothed them down to his chest. His entire upper body lowered with his hands, his head coming to rest at the crook of Ivan's neck. His eyes glided over Ivan's notes, retaining the information they landed on.

Having eidetic memory was a blessing, only now he now knew too much about the primary structure of a polypeptide.

"Hey, babe?" Alfred tried, his voice a good half an octave lower than usual and his tone going for husky and alluring.

He was rewarded with a halfhearted, "Hm?"

Alfred rested his hand on Ivan's pen hand, and his lips came right next to Ivan's ear. "Wanna engage in some enzyme-catalysed seduction? 'Cause I feel like reactin' with ya."

There was a momentary silence.

Ivan finally fully turned to Alfred with an amused and incredulous look in his eyes. "What?" he asked, laughter obvious in his voice.

"You heard me," Alfred said, before glancing at the book.

Ivan was distracted.

His moment to strike was now.

Alfred reached immediately over Ivan, grabbed the book off the table, before springing away from the chair and towards the bed. It took Ivan a moment to realise just what had happened, but when he did he whirled around to face Alfred.

"Alfred, give me back the book."

"Don't think so," Alfred drawled, already halfway across the room.

"I need to study!"

"Ha, right, like you don't already know that - ooh, 'examples of the secondary structure of an enzyme are alpha-helices and beta-pleated sheets,'" Alfred read out loud. "Ok, to be fair, even I know that."

"Alfred," Ivan sighed, clearly resisting the urge to pinch the bridge of his nose.

"Let's skip this, this is boring. 'PCR - polypeptide chain reaction - is used to create multiple copies of a sample of DNA.' There's one other chain reaction I want to happen today."

"Al-"

Alfred had a devious thought. Ivan had once decided to have sex right when Alfred had a project to finish about the Cosmic Microwave Background Radiation, and so now was his time for a payback.

Ivan would never ever look at DNA the same way he used to.

Alfred tone fell to sultry, and he read a few sentences only to lift his eyes up to a disappointed Ivan.

"Mmm baby, biology is such a sexy language," Alfred teased, before flipping through a few pages and dropping the book to the side. When he saw Ivan begin to make his way to the book, Alfred stood in Ivan's way. Placing a hand on his chest, Alfred smiled and shook his head. "I can help you study."

"Alfred, what on Earth-"

Alfred pushed Ivan onto the bed before straddling him.

"DNA primers attach at the desired location-" Alfred said as he began kissing and nipping at Ivan's neck- "to allow DNA polymerase to link to the chain and begin the elongation process." Alfred's hand wandered down to Ivan's crotch, and he hummed happily. "I know something that's gonna elongate in a bit."

"Alfred, for God's sake-"

"What? I'm helping you study in a very memorable way!" Alfred countered with a grin on his lips. "You can't say we don't fit together like complementary bases!" Alfred was pulling these terms out of thin air, basing them on rough guesses of what they might mean.

But the moment he felt Ivan's dick twitch under his hand, he knew he had won.

Well, after a good win was always time for a good celebration.

"Don't need no helicase to unzip these jeans," Alfred said and grinned as he tugged down Ivan's jeans' zipper. Ivan fought down a laugh and a groan as Alfred's hand brushed over his already growing erection.

"Alfred - bozhe - give me ten minutes and I can join you-"

"ATP is broken down to release energy - and we're gonna break down lots of that in a moment," Alfred grinned. "You are not going anywhere until I'm done with you. You know the material, you have it handled, and now it's my turn." He began tugging Ivan's jeans off, and despite the protests he kept giving Alfred, Ivan lifted his hips to help Alfred in his task.

"I need five min-"

"Don't care, because I need you to fit your substrate into my active site," he said as he pulled the jeans down Ivan's legs to reveal his briefs.

"Alf-"

Alfred stopped Ivan from speaking, holding a finger to his lips and keeping a straight face. "I will use a competitive inhibitor if you don't."

"A wh-"

"A vibrator, if you needed clarification, you so-called 'biology student'." His grin widened as Ivan started laughing. "Glad I can entertain."

Ivan sighed in defeat. "Well," Ivan smiled, "An inhibitor's effect can be lessened by adding more substrate."

Finally, Ivan had relented.

"I have no qualms against that, Mr. Big Substrate."

Ivan couldn't hold his laughter down any more, and Alfred began to make his way down Ivan's body, pulling the briefs down at the same time. "I have a feeling you're going to enjoy feeling the induced fit mechanism," Alfred smiled.

When Alfred's mouth turned to other duties than tainting Ivan's biology key terms with his allusions, Ivan's back curved off the bed and he quickly (and gladly) forgot all about studying for the rest of the evening.

Biology references, explained:

- Primary structure of a polypeptide - a polypeptide is what makes up proteins, and they have different levels of structures, this being the first one.

- Enzyme-catalysed seduction - this is supposed to be enzyme-catalysed reaction, a set of biological and chemical reactions (an enzyme is a substance that speeds up a reaction and makes it happen easier, it is a catalyst).
DNA primers... DNA polymerase - all related to the process of replicating DNA.

- Complementary bases - in DNA, the two strands of the "ladder" complement each other, in pairs of bases - A goes against T and C goes against G, and only that way.

- Helicase is an enzyme (thing that speeds up a reaction) that is used to separate the two strands of the DNA ladder when needed. It is often said to "unzip" the DNA.

- ATP is the molecule which is the source of energy for humans that we get from food, when it is broken down into ADP it releases energy.

- Substrate/active site - an reaction catalysed by an enzyme uses both of these. The substrate is the compound that reacts, and the enzyme acts upon this compound/substance to allow it to undergo the reaction. The active site is where the substrate attaches to the enzyme, it is where the reaction occurs.

- An enzyme's activity can be stopped by inhibitors, which "compete" with the substrate to "get the enzyme's attention" and then prevent it from acting on the substrate.

- With competitive inhibition, if you add more of the substrate, you can stop the inhibitor's effect.

- Induced fit mechanism - there are two theories as to how an active site fits with the substrate, and this one dictates that the active site changes slightly and melds to attach and fit the substrate.

- The title is a pun because "Reaction Kinetics" is the study of reactions and how fast they occur - catalysis (use of enzymes and other substances that speed up reactions or allow them to occur easier) falls under this category. And in physics, "kinetic energy" means the energy gained when an object moves and gains friction.