AN: I'm struggling with science. Revising for exams is a pain in the neck and I haven't got a clue what half the stuff I'm meant to know is. So, to motivate myself, I'm writing these: a load of stories where Mello explains to Matt various aspects of science. I don't really know how they're gonna turn out, but for now it seems to be working, seeing as I have to learn what I need to know before I can write Mello teaching it. And I like the idea of Mello being a good teacher. And also because it's 'educational' this is a good excuse to be writing stuff when I should be working. :D This first one was going to go into more detail, but it was taking too long, so I've split it into two chapters.

Oh, and if there are any mistakes, please please please please please correct me, otherwise I really am going to fail science.

Other than that, hopefully, enjoy reading!


LESSON ONE: Genes, Jeans and DNA

It was a quiet, dark night at Wammy's House.

Which in itself was a feat to be proud of.

The usual routine chaos that took the form of Mello and/or Matt torturing Near in as horrific a way as possible had been firmly prevented by Wammy and the threat of even more horrific punishments given their mountains of unfinished (or in Mello's case, completely untouched) homework.

If it had been Roger, they would have swayed at all, but Wammy . . . well, some people even Mello had to make exceptions for.

So as a result, the orphanage took a respite from the double M's mischief that night, whilst the two locked themselves into their bedroom and unwillingly attacked Mt. Homework.

Matt was struggling rather more than Mello appeared to be.

That was the thing about the blonde, Matt reflected as he flicked feverishly through his biology textbook whilst eyeing his Gameboy longingly. Being the rebellious ten-year-old that he was, Mello never actually worked in class even if he was begged by Roger on his knees. He might have done if the begging included chocolate, but Roger didn't understand the pros of bribery.

Matt pulled at the strap of his goggles in annoyance.

He would never have been able to get away with mucking around in class 24/7 – his rank as third smartest kid at Wammy's was generally due to the hours of work he put in Amongst his hours of gaming, of course.

But Mello . . . Mello was naturally smart. He didn't need to pay attention in lessons, and still kept up his reputation as Number Two. In fact, the only time Matt ever saw him actually work was when 'Near' and 'winning' were involved.

Or chocolate.

How he managed was a mystery to Matt. Perhaps he secretly did study, late at night, whilst his partner-in-crime was busy snoring. Maybe he had a photographic memory to help him learn stuff quickly.

Whatever it was, Matt wished he had a key to Mello's genius brain more than anything.

Science was just too complicated . . .

After another minute watching words swim in front of his goggle-covered eyes, he gave up.

"Help," he turned to Mello bleakly.

Mello, too busy snapping squares of chocolate with his teeth whilst he stabbed at the keys of a graphic calculator, ignored him.

Matt counted to sixteen in his head, then tried again.

"Mellooooooooooo," he drew out his name in as pleading a voice as possible.

Mello didn't look up. "What?" he snapped, tone dark.

Matt pouted. "Can you help? Pleeeeeaase?"

With a dramatic sigh, Mello swivelled around his chair. "Help with what?"

"My biology homework."

Matt arched an eyebrow. "What is it?"

"Genes," Matt moaned, slamming his textbook shut for effect.

Mello's expression turned distasteful as he leaned back in his chair. "I hate jeans. I can't wait till I'm old enough to leave this dump and Roger doesn't have a fucking say anymore and I can finally buy some leather pants."

The corner of Matt's mouth twitched, but he tried to keep his face serious. "No, not jeans, dumbass, genes. Biology genes."

Mello smirked. "Same difference, asshole."

Matt felt like wringing his hands in despair, but then Mello would have called him a drama queen, which coming from the chocolate gremlin was just hypocritical.

Instead, as he didn't have time for arguments, he settled for rolling his eyes. "No, seriously. Please Mel – I neeeeeeeeed help."

Mello grimaced and slid his chair across the room to Matt's desk. "Okay, okay, if you quit calling me 'Mel'. And stop elongating words. Your whining is giving me a headache."

"Deal!" Matt beamed.

Mello heaved an enormous sigh and bit off another square of chocolate. "Okay," he said around the piece of heaven deliciously melting in his mouth. "What do you need to know?"

"Everything about genes," Matt answered promptly, leaning forward.

"Please tell me you know what a gene is?"

Matt creased his forehead. "Vaguely," he told him slowly. "I think I was busy getting eaten by the octopus-things in Near's Pacman game at the time . . ."

Mello stared at him.

Then he reached for a piece of paper and stole Matt's pen.

"I think we'll have to start from square one," he announced grimly, taking another moody bite of chocolate.

"Okay," Matt shuffled closer so he could see the paper clearly.

Mello drew a circle on the paper.

"This is a cell," he informed his goggled pupil, then paused. "You do know what a cell is, right?"

Matt threw him a look. "A cell is the smallest unit of an organism that is able to function independently." He recited, textbook-style.

"Right," Mello nodded. "And in the center of most cells there's a nucleus."

"Yup," Matt agreed. "I knew that."

Mello ignored him and drew a smaller circle inside the first one. "So this is the nucleus, okay?"

"What type of cell is that?" Matt asked, slightly off-topic.

Mello glared at him. "It doesn't matter. No, wait . . . it does . . ." he took another bite of chocolate. "To make things easier later, let's say it's any cell in the body apart from the gametes."

"What's a gamete?" Matt asked innocently.

"Sex cell."

"What's a - "

Mello chucked a pencil at him. "Matt," he interrupted in a growl. "Please. You cannot be as stupid as you look."

"What?" Matt widened his eyes behind the goggles. "I was asking a perfectly legitimate question. What is a - "

"Okay, okay, they're sperm and egg cells! Just do me a favour, shut up, and don't you dare ask the stupid question I know you're about to ask just to piss me off!"

Matt grinned. "What are . . ." he began but trailed off as the look on Mello's face told him he should start fearing for his life.

"We are not turning this into a Sex Ed lesson!" the blonde hissed fiercely. "Now, d'you wanna learn about genes or not?"

"I do, I do!" Matt cried hastily. "Please continue, Mello-Sensei!"

Mello rolled his eyes.

"Now in the nucleus of each cell, there are a load of chromosomes," he drew a giant 'X' next to the cell and an arrow from it pointing to the nucleus.

"What's a chromosome?" Matt interrupted.

"Shut up. I'm getting there." Mello shoved the end of his chocolate bar into his mouth, crumpled up the wrapper and threw it at Matt's head. "Chromosomes are made up of strings of genes." Mello drew a load of scribbles coming off the chromosomes. "Those are meant to be the genes."

Matt peered closely at the paper. "Mels, your drawings suck. How can those be genes?"

"I thought you didn't know what a gene was," Mello snapped back agitatedly. "So how could you know?"

"I don't," Matt replied happily. "But if that's a gene, I gotta admit, I'm disappointed."

"You. Shut up. Now." Mello's voice was a deadly growl. "Or I'm stopping this helping-business before you have time to utter 'Mels' once more."

Matt zipped and locked his lips.

"Good," Mello turned back to his scribbles. "Now, genes are instructions. Each one determines a particular characteristic. Like your eye color or whatever. Got that?"

Matt nodded, but stuck his hand in the air.

"What?"

Matt unlocked and unzipped his lips. "How many chromosomes do you have?"

"In each cell? Forty-six. They come in twenty-three pairs – two versions of each chromosome."

"So where do you get your genes and chromosomes from?"

"Your parents. You get half from each – that's why they come in pairs."

"Okay," Matt said slowly.

"Can I continue? Or are you gonna ask another question?" Mello huffed. "And I need chocolate. Pass me a bar from my desk."

Matt hurried to comply, then waited as Mello tore at the wrapping and took a bite.

"Right," Mello said. "Now we get DNA. This is the chemical that makes up the genes. They carry the chemical code telling a cell how to work, and also the genetic code." From the end of the gene-scribbles, he drew the famous DNA double-helix.

"Oh!" Matt enthused. "I've seen that before! Linda was teaching Near how to make friendship bracelets in that shape!"

Mello face-palmed, then tried to be teacher-like.

"So, er . . . can you summarize what I've taught you?"

Matt pulled off his goggles, scrubbed them with his sleeve seriously, then put them back on again. "Yes sir! DNA is a spirally-shaped chemical-thing that tells cells how to work and makes up genes which are instructions to give you certain characteristics. Strings of these make chromosomes which are found in the nucleuses of each cell. In each nucleus there are twenty-three pairs of chromosomes, half from each parent! That's everything, right?" he rattled off in one breath.

"Er, yeah, something like that," Mello said weakly. "Only, it's 'nuclei' not 'nucleuses'."

"Oh yeah, I thought it sounded stupid," Matt nodded, then suddenly frowned. "Hang on, why did it matter that the cell you drew wasn't a – what did you call it? Ga . . ."

"Gamete? Coz gametes only have twenty-three chromosomes. Not forty-six."

"Why?"

Mello sighed. "Think, idiot. When do the twenty-three chromosomes from each parent mix in the first place? How d'you think they do?"

"Uh . . . oh!" Matt's eyes went very wide. "When - !"

"Yes," Mello leaned back in his chair, snapping off some chocolate with his fingers for once and dropping it into his mouth. "They're called 'sex cells' for a reason. They mix to form the twenty-three pairs and there you go. The recipe to make you, in one tiny, microscopic cell."

Matt nodded. "You know what? I think I understand all this now."

"Good," Mello groaned in relief and finished his chocolate. "I'm worn out. I'm gonna sleep. Don't disturb me."

"'Kay! I'll just finish the homework then!"

As the goggled maniac turned back to his work, Mello sighed, stripped, pulled on his pyjamas and collapsed on his bed. He had about five minutes of peace before a wail came from the other side of the room.

"Melloooooo!" Matt cried despairingly.

Mello's disgruntled "What?" came out muffled by the pillow.

"What's an allele?"

Mello moaned. "For chocolate's sake, Matt . . ."

"Please?"

"No, I'm sleeping," Mello grunted.

Then he relented. "I'll help you tomorrow."

"Yay!" Mello could practically feel Matt beaming. "Thank you, Mello-Sensei!"

"I almost preferred it when you called me 'Mel'," he muttered.