A Bad Boy can be good for a girl.

Lily Evans has read enough literature and comforted enough broken hearts to know this is true. Every girl wants to think that they're the one. It's them who will straighten him out; it's her that he'll change for.

And the Bad Boy knows this. He takes advantage of it.

He knows exactly what to do to get what he wants. As soon as he receives what he's after, he leaves, uncaring about (and perhaps not even knowing) the debris he's leaving behind.

A Bad Boy can be good for a girl. It's a silent rule she's always followed. The saying itself is not the rule, but the several implications behind it guide her actions regarding the opposite sex.

A Bad Boy will always be a Bad Boy.

A Bad Boy will never change…for anyone.

Never, under any circumstances, get involved with a Bad Boy.

As with any set of rules, however, there is always one exception.

James Potter has never been one for rules.

And James Potter is the quintessential Bad Boy.

He drinks.

He smokes.

He bullies.

He doesn't care…about anything.

He's never seen to do any work.

Lily Evans was always told to stay away from Bad Boys. And she never had trouble obeying. Until James Potter.

She'd tried her best. She really had. And she had honest-to-goodness started out hating him. It was easy to do back then. He was an obnoxious little brat his first few years, but then…

Puberty struck.

And James Potter became a Bad Boy.

It had started with the puberty. James hadn't really noticed what he looked like until the start of his fourth year. Suddenly, girls were staring at him. Girls were whispering about him. And girls wanted to date him.

He was inexperienced at first. But that had quickly faded as he learned more and more about the opposite sex. He became so used to being in demand. He liked it. What hormonal teenage boy wouldn't?

With this new, astronomical rise in popularity came the partying. Sirius Black was always well-connected, and managed to lay hands on cases and cases of liquor for every party. James had started drinking. And partying.

Soon after, James had taken up smoking. He'd caught a glimpse of a Muggle inhaling a cigarette on a brief trip through a Muggle town during the summer before his sixth year. He'd discreetly bought a pack the week after and had been smoking regularly since.

A short while later, he became sloppy. He didn't care how he looked, really. And that made him even more irresistible.

To every girl except, say, Lily Evans.

She could not stand him. That was what she told everyone who would listen (and even a few who wouldn't).

And at first, she really did detest him.

But she was still a girl. With eyes. And hormones.

She'd never admit it to anyone, but James Potter was attractive. Damn it, he was downright sexy.

But he was still a Bad Boy.

Lily's mother had always warned her about Bad Boys. "Stay far away, my little Lily Flower," she'd been warned, "They'll cause nothing but pain and trouble. You're a Good Girl, Lily. I don't want to see you hurt."

Lily was a Good Girl. And Good Girls stayed away from Bad Boys.

And she wanted to. Merlin knows, she wanted to.

Her brain screamed at her, Stay away! She had the overwhelming urge to run whenever he started sauntering over to her. She wanted to never see him again. She wanted to stay away.

But an equally strong part of her wanted to fling her arms around his neck and crush her lips to his. She wanted to snog him senseless. She wanted to run her fingers over his muscled, toned skin. She wanted him.

When he strutted over to her in the common room, it was these two sides that fought for control. She'd end up staying where she was at, trying desperately not to look at him.

"Tell me how you do it, Evans," he'd say, giving her a grin with just a hint of innuendo.

She'd try to come up with a caustic remark, but the side that wanted to do unspeakable things to him wouldn't let her. She'd end up making some sort of strangled squeak, causing James to smirk.

"Tell me how you make everything you do look so damn sexy."

She'd flush and splutter, trying to disguise the pulse now racing twice its normal speed. She'd try to disguise the sparks shooting down her limbs and the fantasies now playing inside her head.

She'd swear he could tell what her body was doing. He'd wink at her slowly before leaning back up. Her eyes would dart to the strip of exposed flesh between his rumpled t-shirt and jeans that hung a little too low on his hips. She'd lick her lips unconsciously and her heart would leap to her throat.

And even though by this time he was already halfway across the room, she could swear that he knew exactly what she was thinking.

Lily wanted to ignore him. She really did. But she couldn't.

And it scared her.

She wanted to follow her rules. She didn't believe that Bad Boys could change.

But she wanted to. And it was her one observation that led to this desire.

James was not a chaser. On the Quidditch team, yes. But not in the real world. Girls flocked to him. He didn't need to go after them.

He did chase very rarely. In fact, she could only remember one other time.

He'd been after Madeline Starr. She was an intelligent Ravenclaw sixth year, same age as him. He'd gone after her for a couple of weeks, stunning everyone at Hogwarts. Had he finally changed, they asked. Was she the one?

She wasn't, as it turned out. As soon as he'd gotten what he was after, Maddy Starr was left alone. And brokenhearted.

James Potter did not chase.

Except when it came to Lily Evans.

He'd been harassing (or flirting, as her hormone-driven side liked to call it) her for years. He would not leave her alone.

He never did this with anyone else.

And so a small part of Lily hoped that somehow, he would prove her wrong.

She wanted him to change.

But didn't believe he would.

If only she knew…

It started small. In fact, it started with a tie. A tie that normally hung undone around his neck like some sort of bizarre necklace. Slowly, ever so slowly, this tie morphed into a knot. Which became a neater knot. Which somehow turned into a (somewhat) neatly tied tie.

It was a very subtle transformation.

The clothes went first. Ties became tied, shirts started tucking into pants, and wrinkles started to fade.

This did not happen overnight. Nor was it a conscious decision on James' part.

No, it was more like he…forgot. He forgot that he needed to be messy.

The plus he discovered was that girls loved a neat guy.

Next went the smoking. His cigarette consumption ever so slowly dwindled week by week until one day…he forgot to buy another pack. And just didn't pick one up again.

He discovered that girls hated the smell of cigarette breath. And the loved a bloke with fresh breath.

He still partied. But he didn't drink as much as he used too. Make no mistake, he still got piss drunk. But maybe not as much as before. He simply…forgot to keep drinking.

Girls also enjoyed a boy who did not reek with liquor.

These changes were subtle and slow, taking a grand total of a year to complete. And they were not conscious transformations. No…he just forgot who he was supposed to be. He forgot who Bad Boy James was.

Then came the personality.

James was still sarcastic and crude. Maybe just in lesser concentrations now. Suddenly, Lily was seeing something new.

No, not something new. Something he'd never shown anyone (besides his three friends), least of all a girl.

He did care. He cared about his friends. He cared about his parents. He cared about the war. He'd just never let anybody see it.

He was loyal. He went to hell for his friends and back (or at least, just to the Whomping Willow).

He was still a Bad Boy. She knew what he wanted from her.

But she couldn't help but wonder if she was the reason he looked so different.

Yes. While others may see only a slightly watered down James, she saw someone worlds different than the James of before.

Even though he was still a Bad Boy.

She still felt a haunting sense of dread and fear jolt through her whenever she saw him.

And she still wanted to snog him within an inch of his life.

Oh, the trials of being a teenage girl.

A Bad Boy can be good for a girl (only to get what he wants).

Sometimes, there are exceptions.