A/N 1: I'm in love with the chemistry between Selena and David on the show. I'm not so in love with the whole blood-siblings thing (no offense to fans of the ship). So, I 'm doing the whole cliché, we're-not-related-thing to reconcile these things. Hope you enjoy.

A/N 2: Sorry, for those who are still waiting for Where the Heart Is. I'm definitely going to continue, but, this was a plot bunny that would not stop tormenting me. Plus, honestly the next chapter of WTHI is a tough one, so I guess you could call it 'fic procrastination' as well. Don't hate me ::covers head::

***

Part One

***

It started on a Monday, like all shitty things do.

Justin was tutoring her in science, because she was failing, and it was something she really wanted to improve in. (Also, Theresa had threatened-both in English and Spanish--that she'd be grounded forever if she didn't pass her test).

They were in his bedroom--the fortress of all things dorky and uninteresting--him standing by this stupid rolling dry erase board, and her laying listlessly across from him on his bed, trying to learn how to fall into deep, deep sleep with her eyes open.

She was just about to give up, and settle for deep, deep sleep with her eyes closed, when he hissed, "Alex. Are you even listening to me?"

"Umph, uh, yeah, totally," she chirped, head jerking up, "Science…rocks."

Alex lifted her thumb, pointer, and pinky fingers in a 'rock' gesture, and he rolled his eyes.

"I don't even know why I waste my time with you."

He huffed and tossed his marker to the floor--one of his 'man-fits' as she often referred to them--and she sighed. Sure, she loved annoying the hell out of him, but he was being kind of sweet and helpful by teaching her and all. Justin was far from Mr. Popular, but even he could think of better ways to be spending his night. She wrestled between the usual thrill of aggravating him, and that other prickly, irritating need to see him not upset, before sitting up on his mattress.

"I'm sorry," she said softly.

He turned to her, from where his back had been stubbornly facing her, and she pursed her lips, pouting gently for him, in that way that he'd never admit could always thaw him out.

He glared at her.

Crossed his arms.

Grunted.

Then his eyes flickered softly between agitation and giving-in, and he sighed.

"Fine, whatever," he mumbled all cool like. "I'll keep helping you. But, only for mom. And, the integrity of science. Not you."

She nodded earnestly, biting back a smile. "The integrity of science needs you."

Justin stared at her for a long moment, eyes narrowed like he was robo-scanning her for any insincerity, before he nodded slightly. "Right. Of course."

"Of course," she said again.

He sent her one last glance, and she decided to actually open up her biology book (you know, just for show), as he reached for his marker. She noted with a smirk that his shoulders were a bit straighter, his chest puffed out slightly as he began again.

He could be so easy, it almost hurt sometimes. But, mostly, it was just fun.

"Right, okay, so where was I?" Justin mumbled.

"Something about genetics and families, blah blah."

He chuckled slightly. "You're just like a sponge," he said with his hands.

"Hey, I am not spongy." She pointed her unused pen at him like a threat, "I've been weight-lifting."

"That's so not what I meant, but never mind." Justin shook his head slightly and pointed back to the board. "Okay, so genetics."

"Right, got it," Alex blurted, scribbling onto her blank notebook page.

Justin sent her a tired, but patient look and waited for her to finish.

"Alright, so now that we have the subject down," he said, earning an eye roll from her, "Let's move on to something that will actually help you pass your test."

He turned to the board and Alex watched as he drew two intersecting lines, one vertical, one horizontal. Her eyes lit. "Oooh, are we going to play tic-tac-toe?"

He snorted. "Uh, no Alex. We need another line for that, and last time I checked, Mr. Bower didn't give extra credit for drawing kid games in the margins."

"Or doodles," she offered sagely.

"Exactly," he said, lips quirked. "Okay, so this is a-"

"Oh, oh, wait," Alex blurted, bouncing slightly, "I remember this one. It's a-a Puny Square or whatever. And, you can put in all those letters and stuff and add 'em up."

"Close," he answered, although he was wincing slightly. "It's a Punnett square…"

"Right, that's what I said-"

"And, you can't add letters--not without wizard math anyway."

She scrunched her nose at him. Who in the world would want to do that? Oh, right, Justin.

"…it's really more about the genotypes, and how the alleles interact with each other. So, here, in this example…" He scribbled letters on the board, and Alex scribbled on her own pad of paper, trying to keep up. "…the alleles are different, so the offspring will be heterozygous. And this… will be the dominant trait."

Her eyes glazed over--even though she was trying really, really hard to stay with him (well, at least moderately hard anyway). Justin seemed to notice this and frowned as he turned back to her.

"This is a little over your head, isn't it?"

She chewed her bottom lip. "I'm not even sure if you were speaking English."

"Ah, okayyy." He tapped his finger on his chin for a moment, and she could see the dorky wheels turning in his head. "Okay, how about this? Let's start simple."

She nodded. "I like simple."

He pointed to himself. "I'm your brother."

"Really?" she asked with spiked brows, "Because I thought you were just some strange, geeky boy who lived with us. You know, like a foreign exchange program for nerdy, under socialized children…?"

His brows furrowed, which was always cute and she loved making him do. "Hilarious," he deadpanned. "But, anyway, as I was saying… we're siblings. So biology teaches us that there are certain traits that we should have in common."

She snorted. "Like what?"

"Well, definitely not intellect, or sophistication, or responsibility--"

"Or, charm, good looks, creativity, popularity. Or even basic social sens-"

"Okay, so we get the point," he said over her with a scowl.

She smiled prettily at him, eyelashes batting as he rolled his eyes.

"The point is, as indescribably bizarre as it may seem, we share many genetic traits." He pointed to the board. "And, this is basically just another way of describing that, and explaining how it happened."

"Hmm." She pursed her lips. "That actually seems…almost interesting."

"Exactly." He smiled again, this time big and genuine. She couldn't stop her own lips from tilting in response. "See, science isn't so boring and lame once you understand it a little better."

"Okay, answer man. So, tell me, what in the world do we have in common? I mean seriously, we look so different, half the time people think we're dating, or something."

She twisted her nose like that was the most disgusting thing ever--which it really was, on so many levels--and Justin sent her a similarly distasteful look.

"Yeah, I know," he said a little quietly. "I guess we do look a little…different."

"Uh, ya duh. And, you're so much smarter and more disciplined than me or Max--not that I'll ever admit that aloud again," she inserted off his surprised look, "S'just weird."

"A little. But, we shouldn't base things off appearances. We should base them on science. Because, science-"

"…never fails," Alex mumbled tiredly.

"Good to see you're catching on." His eyes widened suddenly, lighting up. "Hey, you know what would be fun?"

"Ditching this and watching America's Next Top Model?"

"Alright, so fun for me," Justin said. "I bet there's some sort of spell we could do, to make this more interesting. A way we could actually see all our genes and everything."

"You're right," she mumbled.

"It sounds cool?"

"No, I meant that it would only be fun for you." She sat up, her foot flirting with the carpet, "So, I'm just gonna flip on Tyra-"

"Alex."

"Ugh, fine."

"Okay, just give me a moment, while I search P.U.S.D."

Alex grimaced, rolled on her back, and whined. She hated when he used that stupid thing. She hated when he even said it. P.U.S.D. (Potentially Useful Spells Database), was some lame-tastic project Justin had pushed their Dad into last year. He'd collected all the obscure, and of course, 'potentially useful', spells and put them into some computer program.

"Got it," Justin cried.

She lifted her pointer finger and spun it. "Yippee."

"Okay, stand up."

"Do I have to?" she whined, "I'm comfortable."

"That depends," Justin said casually, "How do you feel about summer school?"

She pulled a face at him, but acquiesced, sliding slowly off his bed.

"Alright, here we go." Justin slipped the index card off of his desk and read, "'Families share and families care, show us how we're similar on the board up there."

There was a rush of wind (which sucked, because she'd just done her hair), and the board lit up with all those weird charts and DNA models she'd ignored in biology class.

Alex groaned, "Ugh, this is so boring it's yucky."

"Just wait for it," Justin said.

"Wait, for what? Death by a thousand models?" She lifted her hands, checking her fingernails, (When was the last time she'd gotten a manicure?), only to catch Justin glaring over the tips of her fingers.

"No," he said priggishly, "It can take a while, but it's going to connect our traits, show us how we're-"

"FAMILIES CARE AND FAMILIES SHARE, BUT THESE TWO PEOPLE ARE NOT A PAIR."

Justin squinted at the singing board, "What?"

"YOU'RE NOT RELATED, IDIOT!" the board cried, before dimming and returning to normal.

Alex folded her arms and sent him a smug look, "I thought science never failed?"

She smirked, (because, honestly, nothing floated her boat more than seeing Justin wrong about something). But he wasn't smiling. Or even glaring, or bumbling, or ranting at her. He was just…still. Almost pale.

"Dude, chill," she said again, this time more quietly, "It's just one bum spell. I'm sure you can keep using P.U.S.D."

He didn't answer for a long moment, and she felt something tighten in her stomach. This was off, even for Justin. "Justin," she tried again.

"It's not wrong, Alex," he snapped over her. His voice was sharp, tight all of a sudden, and when he finally looked at her, his eyes were hard.

Her mouth parted. "But…but, it said."

"It's not wrong."

He brushed past her, their shoulder shoving slightly, before marching out the door.

***

Justin left the apartment and didn't come back.

Which was strange, and probably should have concerned her, but she'd never understood science or the things that could set off his tantrums, so she ignored it. (Plus, there was a Top Model marathon on, and it was easier to tear apart pretty girls' outfits than even dare acknowledge that sinking, uncertain feeling Justin's lesson had left in her stomach).

When the door finally opened mid-model breakdown, Alex called carelessly over her shoulder, "Finally beamed back from Planet Loser?"

"Alex."

It was her mother. And the desperate, raspy catch in her voice instantly made her head jerk up.

"Mom?" she answered softly. She stood from the couch, the remote dropping to the floor.

"I think it's better if you sit down for this, Alex."

Theresa walked towards her, her footsteps heavy thuds on the floor planes, and Alex had the inexplicable urge to charm herself out of the living room.

Instead she blurted, "Where's Justin?"

For some reason, she desperately needed to know.

"He's downstairs in the restaurant," Theresa said thickly, "Talking with your father."

Her voice shook. "Wh-what are they talking about?"

"Alex," Theresa said again, more firmly, "Please, sit down."

She was about a second from sprinting, literally just making a run for it, charm or no charm--but her mother's pleading gaze held her their. She exhaled, and slowly took a seat besides her on the couch.

Theresa sighed, brushing hair from her face, unveiling even more of her wet, red eyes, and her tired, worn face. And, before she could even begin, Alex just knew it, knew it somewhere deep in her chest, in a place she'd always ignored. "He's not my brother, is he? Not for real."

"No," Theresa answered softly, "Not for real."

***

It happened in the middle of the night, as all crazy things do….

Once upon a time, a loud colicky baby girl was wailing in her mother's arms.

A streak of light thundered, like lightening trapped in a house, and when it cleared, there was a little toddler, a little dark haired boy sitting in the bedroom.

"He's not a stray dog," Jerry had said, even as he'd held the silent boy up against his hip, "We can't just keep him."

"But, he has no home, Jerry. Every boy should have a home. Maybe…maybe he was sent to us for a reason."

And they lived happily ever after.

The End.

***

"So, let me get this straight. A stork, like a literal stork delivered Justin to our house?" Max asked Alex, eyes popping.

"Yeah, uh, something like that," she mumbled hollowly.

"That is so…cool."

"It is not 'cool'," Alex hissed. "It's horrible. Justin's not our brother."

There was a loud silence as her dark eyes collided with his, and Alex watched the grin slowly fade from Max's face, watched it finally start to settle in for him.

"Oh," was all he could say.

She sighed and tucked her knees under herself from where she was sitting on her bed, Max perched silently on the edge. His face was twitching slightly, almost like he might cry, and she felt this sudden ache for Justin to be there, to say something Justin-like and make everything okay.

But, Justin was gone. He'd never come back after his talk with Jerry.

"It's okay," she finally whispered, and it felt like the lamest, most useless thing she could ever could say, "It's…okay."

"How is it okay?" he rasped, his voice catching slightly.

She reached over, slipped her arm over his shoulder, and hugged him as tight as she could. She felt wetness on her neck, and she sighed, rubbing his back, "It's okay."

***

It wasn't okay.

Obviously. She was failing science--and possibly math--but even she could see that.

It was dark and Justin still wasn't home. No one brought it up aloud--(except Max, repeatedly, but he didn't count). Yet, Alex kept catching Jerry sending sad, wary glances out the rain-slicked windows.

"He's still family," was all Jerry had said to her when he'd come back, sans Justin, "He just…doesn't understand yet."

Obviously, Alex thought. Because, honestly, she didn't really understand it either.

***

She woke up with a start.

It was one of those dreams where she was falling again, and when she jerked up on her bed her breath caught, because there was Justin. Standing there, soaking wet, and watching her.

"Justin," was her first thought. And, then, "Creepy, much?"

"S-sorry," he stuttered.

She reached over for her lamp, and the light flickered on.

"I-I wasn't staring," he blurted. "I just was here, and-and you were screaming."

She squinted at him, because even in situations as serious and life-shaking as this, he was still an utter dork. She slipped from the under covers, ignoring the rest of his rambling, and hurrying across the carpet to him.

"…it's awkward, but-oomph,"

She cut him off with a fierce hug, her arms wrapped tightly around his neck like a padlock, and her face buried in damp lapel of his coat. "Oh, my god, are you okay?" she breathed.

"I-I, uh, yes," he rasped.

He stood for a long moment, stiff and still, before finally letting a lone arm slide around her back. She sighed into his neck. "I'm so sorry, Justin."

"It's not your fault," she heard him murmur, "It's nobody fault."

She felt his cold hands on her shoulders, soaking through her night shirt, and she shivered slightly as he pulled back.

"I just…heh," He let out a mirthless laugh, "I just…"

"It's okay, Justin," she whispered over him, this time more certainly, "You don't always have to have something to say, something logical to explain everything."

"No, see, that's exactly the problem, Alex; because, I do. I need it. It's the only thing that keeps me sane, to be able explain things."

"Justin-"

"And, now everything is…ugh," He sighed and ran both hands through his hair, "…it doesn't make any sense."

He moved away from her, towards her door and she felt a tug her in chest and followed him. "Why does it have to make sense?" she asked hurriedly, "Who cares if doesn't make sense? You're still my brother, Justin. You're still family. Even if 'Lord Science', says otherwise."

He turned back to her then, almost a jerk, and she was surprised to see his face flash with anger. "Science isn't a 'gossip magazine', or 'Tyra Banks', okay? It's not an opinion, or a suggestion, it's just right. It's just fact …it's just flesh and blood, and we…" He stopped, his eyes flickering darkly for a moment. "You just don't understand. You never understand."

That stung more than it should.

"That's not fair," she whispered. "Maybe you're the one who doesn't understand."

He rolled his eyes, and she felt like hitting him. She hated when he did that. She hated when he just brushed her off like she was some silly, clueless little girl. Especially when it came to something so huge, like this.

"Nothing's changed, Justin. Nothing has to change if you just let it go."

"Right," he said darkly, "I'll just…" He waved his hands around sarcastically, "Let it go, and completely ignore the fact that my whole life has been a lie. Just a small, tiny, itty bitty fact. God, you can just be so…stupid sometimes."

She flinched, because Justin never spoke to her like that, no matter how much she messed up, or how angry he got, she was still always his 'Alex'.

Her lip shook slightly, but she swallowed down the lump, and watched him as he stared hotly back at her. When she didn't strike back, didn't say whatever he was expecting from her, he grunted and turned for her door.

She huffed.

"So, what," she called after him, " You're just gonna disappear into the shadows again, like some lame Batman? I know we're just you're 'fake family' and all, but we still care where the hell you are at night."

She grabbed his arm and pulled a little meanly. "Justin-"

"I'm not leaving. I'm just going to my bedroom, if that's okay with you?" he said sarcastically.

She didn't let go right away, like she didn't believe him--which maybe she didn't--so he tugged his own arm away.

"Goodnight," he said stiffly and slammed the door shut.

***

"Alex! Alex!"

"Ughhh, what?" she moaned into her pillow.

Wasn't it bad enough the word was ending? Couldn't she at least get some damn sleep?

"Justin's moving out," Max cried, "Like right now."

"What?"

She burst out of her bed, pillows and sleep forgotten, and was sprinting through the hallways before Max could even finish his spazzing. She reached Justin's door, panting, to find Theresa and Jerry already standing there, speaking with him.

"…see how things go," Jerry was saying.

"You're moving out?!" Alex cried, cutting Jerry off.

Justin blinked, back straightening as he turned from his suitcase. "What? No. Of course not."

"So, what?" She asked, still a bit breathless, "The suitcases are just for decoration?"

He sighed, frustration flickering in his eyes, and Theresa stepped in for him. "Honey, Justin's going away for a little while. To help process things."

She scowled. "Why can't he 'process' things here?"

"Alex, you're being a brat, stop it," Justin said.

"No, you 'stop it'," she hissed back at him, (which yeah, maybe was tad bit childish).

"Alex-"

"Maybe you should wait outside for a moment," Jerry said over him. "Until we sort everything out?"

"Right," she said dryly, "Don't mind me. I'm just some random chick who's not affected by this at all. Please," she said with a grand hand gesture, "Carry on."

"No, stay; I insist," Justin said tightly, "I mean, why shouldn't you stay when you've already provided such helpful and productive insight."

Her jaw flexed and then she took several sharp steps towards him. "Don't take this out on me, Justin. Don't beat up on me, because your life sucks all of sudden."

"Alex," Theresa hissed.

But, Alex ignored her, her gaze and her attention solely on him. "And, if you're gonna keep being an ass like this, then maybe it would be better for you to just not be here anymore."

Theresa gasped, Justin's eyes widened, and then Alex took her own turn slamming the door shut as she stormed out.

**