AN: I needed fluff after reading CoLS because too many feels from that book. D: I've always thought this pairing was cute, so I decided to write Sizzy.

Simon used to think that he'd need some sort of cosmic intervention to get a girl like Isabelle. Or really, any kind of girl. And okay, he's verging on attractive now that he's a vampire and, yeah, Isabelle has a thing for Downworlders, but she's still Isabelle Lightwood: breaker of hearts, raiser of penises. He's wondering why she ever agreed to go out with him in the first place, but he's even more baffled about the fact that they seem to be sort of inseparable now. Like serious couple inseparable. Simon doesn't know how to handle it because when have girls like Isabelle gone out with guys like him? Except in, you know, the wet dreams of geeky boys everywhere.

It's no surprise that after they start going steady (he thinks?), he winds up sitting in Clary's room, trying to figure out what the hell is going on.

"I think I'm dating Isabelle now," says Simon.

"Haven't you been dating her?" Clary raises an eyebrow over the sketch pad she's currently drawing on.

"No, I mean seriously dating. I slept in the same bed as her while she was in her underwear. And I told her about Star Wars." Clary takes one look at the incredulous expression on Simon's face as he says this and breaks into a fit of giggles.

"Well, God knows there's nothing more romantic than Star Wars," she says sarcastically. "You didn't spend that time regaling her with sweet romantic sentiments? Like, 'Oh Isabelle, such wondrous hair you have. And your eyes – such beautiful pools of light. Your legs go on for days, and your breasts, don't get me started – '"

"Will you stop that?" Simon grabs the sketch pad from Clary in exasperation. She's drawing Jace – of course. "I'm serious here. I'm being completely and totally serious. You have to help me, I'm begging. Tell me what to do." Simon finds it kind of strange that he's resorted to asking his ex-girlfriend for help, but Clary is Clary, and he figures "best friend" trumps "ex-girlfriend." And besides, she's dating the nuclear bomb of boyfriends while he's dating the female equivalent. If anyone knows how to keep a girl like Isabelle, Clary should.

"Okay, here's what you don't do. You shouldn't stab her with a magical sword and turn her into the human torch." Clary manages to grab the sketch pad back from Simon and sits back in her chair with a triumphant smirk on her face.

"Oh, what brilliant advice."

Clary shrugs. "I have nothing for you, my friend. Love is weird and crazy and confusing. Maybe you should start telling her about Lord of the Rings next?"

And though Simon should have realized that he's pretty much on his own after this conversation, he can't help but hope that someone, someone out there should be able to help him.

Jordan is maybe even worse than Clary.

"Do you think Maia will like this necklace?" He holds out some sparkly configuration of glitter and crystals out to Simon. "Because it's the four-and-a-half-week anniversary of us getting together again, and I want to get her something nice. Thoughts?"

"Er…"

"Okay, fine. You don't like it. I was feeling pretty iffy about it anyway. Not sparkly enough." Jordan places the necklace back on the counter. He peruses the glass cases at the jewelry shop with a single-mindedness reminiscent of his Halo-playing, oblivious to Simon's dilemma. He's been going steady with Maia for a while, so Simon figures maybe he's got some Dumbledore-esque advice on how to keep a girl.

"What do you think about Isabelle?" asks Simon.

"She scares me, honestly. Especially when she's waving that whip of hers around."

Simon sighs loudly. "Exactly. She goddamn scares the shit out of me too, and I'm dating her. I don't know how to act around her sometimes because she's Isabelle Lightwood and I'm just Simon Lewis. So how the hell do I keep her from realizing she can do so much better?"

Jordan thinks for a minute. "Throw her on the ground and make passionate love to her." He nods excitedly. "I heard vampires are just naturally great in bed. Might as well test that out. But – you know – use a condom. Though I guess with someone like Isabelle, she's got that covered. Wait, does vampire sperm even work?"

Simon closes his eyes and resists the urge to bang his head against a wall.

"I'm…seeing someone now?" Simon says uncertainly when he meets his sister for coffee. Simon doesn't drink any, but Rebecca's been a coffee addict ever since she moved away for college. They're talking, yeah, and though things are kind of awkward, he doesn't want to lose Rebecca. They've been through too much together, and though his mom doesn't get the shit Simon's going through, Rebecca's trying her hardest to understand.

Rebecca laughs. "Is she pretty?"

He groans and buries his head in his hands. "Really stinking beautiful."

"So why do you sound so unhappy?" She sips her macchiato and looks at Simon imploringly.

"Rebecca, have you ever dated someone you know is completely out of your league? Someone who's done things and experienced things you've never even heard of? Someone you know could do so much better, but for some inexplicable reason, they've chosen your geeky ass? I mean, she came over to watch me play Halo and didn't complain one bit. How did nerdy Simon turn into someone who could get someone ten leagues hotter than he is?"

Rebecca taps the side of her coffee cup slowly. "Maybe that's the problem, you know? You always thinking about how she's so much better than you. Love isn't accepting someone in spite of their faults. It's loving them for their faults, all of them. And if you can't see this girl's faults, I don't know how healthy a relationship with her can be."

"Well, she's kind of a bitch sometimes. Closed-off. Doesn't want to fall in love. Kind of stubborn too. Oh, and don't tell anyone this, but her morning breath makes me want to puke."

"See? Next time you're around her, remember all of this," Rebecca says. "And just so you know, though I may be biased because I'm your sister, you've got some pretty great shit going for you too. Who else do I know who can quote directly from Harry Potter while listening to crappy nerdcore bands and playing Call of Duty?"

"No one?" Simon guesses.

"You're a very unique person, little bro. Very."

Simon never thought he'd see the day when this particular Shadowhunter would be slurring his words and gesticulating wildly with a dazed look in his eyes, but here it is: Alec Lightwood is really fucking drunk.

"You want my advice? Never fall in love. Love is for suckers. All that happens is that you wind up seeing him across the room at some party flirting with some vampire – a girl vampire – and when you go up to say hi, he ignores you. Just turns away and talks to his little vampire some more." Alec spits out the words. Apparently, alcohol makes him a lot more talkative than usual because sober Alec would never even contemplate voicing his opinions so freely. "And that," he points at Simon, "is what happens when you fall in love. Because those goddamn vampires are just waiting in the sidelines. Fuck them." Realization dawns in Alec's eyes. "Wait, you're a vampire. But then – " His mouth twists, momentarily confused. "You know what, never mind, you know what I mean, right?"

"Er, yeah?"

"So don't do it," Alec says sagely. "Don't let those goddamn vampires win in the end. Because that's what happens when you fall in love. The girl vampires win."

And though this piece of advice is pretty damn useless, Simon tries to take it to heart anyway. Because though he doubts that the girl vampires will win if he falls in love with Isabelle, seeing Alec drown out his sorrows in alcohol scares Simon more than he'd like to admit. If this is what love is, he doesn't know if he wants any part of it. And though he'd like to see the world through rose-colored lenses, for some reason, he has a feeling that someone as beautiful and worldly as Isabelle will leave him feeling worse than Alec is feeling now.

Maia's kind of amused. "You're seriously asking me for advice about the girl you cheated on me with?"

"You told me that wasn't technically cheating!"

"Yeah, well, that sounds better than 'the girl you were dating at the same time we were dating, but oh wait, that's fine because we weren't dating exclusively anyway'. Plus, it's easier to say."

Simon leans back on the couch and presses the buttons on his video game controller more frantically. "So no advice? Jordan told me I should just have sex with her."

Maia laughs. "Yeah that sounds like him. I mean, I'm not trying to gross you out or anything, but when we're in bed – "

Simon abandons the game in favor of keeping his sanity. "Stop! Shit, just stop!" Simon places his hands over his ears. "Lalala, I'm not listening. I don't want to hear about your sex life."

Maia's cracking up, her game controller sitting on the couch next to her. Now would be the perfect time for Simon to swoop in and crush her in the game, but he's still adamantly keeping his hands placed over his ears. "I think we've established that you definitely shouldn't try to seduce her if you're going to be that prudish about it."

Simon mumbles something incoherent.

"Stop worrying so much, Simon. Just be yourself."

"You mean I should keep acting like a sixteen-year-old geek who's never had any luck with women before and used to get raging mental hard-ons for Star Wars chatacters?"

Maia purses her lips. "Yeah, that."

It's no secret that Simon has never liked Jace very much. He's arrogant and annoying and frankly, Simon is just damn jealous of the fact that he gets along with people when they should theoretically hate him. But Simon's trying his best now because, surely, beautiful people know how other beautiful people think.

"What you have to realize about Izzy is that she doesn't want to fall in love with you. Don't take it personally." Jace waves his hand dismissively. "She doesn't want to fall in love with anyone."

"I got that already." Okay, so asking Jace about Isabelle? In retrospect, probably not Simon's best idea.

"No, but that's a good thing." Simon doesn't really understand, but he lets Jace continue. "I never wanted to fall in love with anyone either, and here I am, a stupid sap who's trying to give you love advice."

"You're not doing a very good job of it."

"Do you really want advice from the guy who can barely kiss his girlfriend because he's so hot he literally burns?"

"Well…now that you put it that way…"

"I can't give you advice. Every couple's different. We're all different meshes of personalities and situations, and we all have our own stories. I mean, look at Clary and me. We started out as brother and sister. You just have to find out how to write your own story with Isabelle."

For once, what Jace says – as much as Simon hates to admit it – actually makes sense. Frankly, he's just surprised that Jace managed to utter something that wasn't a blatant self-promotion.

"Oh," Jace adds, "and if you hurt her, I'm obligated to beat you to a pulp."

Magnus is just as broken as Alec about their split, but since he refuses to actually say anything to his ex-boyfriend about it, Simon isn't one to get all up in their business. He didn't even mean to run into Magnus, really. It's just that they happen to be investigating Maureen's murder of Camille in the same place at the same time. When Magnus sees Simon, he ignores him. He's been ignoring the former Team Good pretty stubbornly recently, which makes it difficult for them to actually get any work done. Certainly throws a damper in their plans to kick Sebastian's ass. But finally, Magnus comes over and clears his throat to get Simon's attention.

"Sherman," he begins. Simon rolls his eyes. "How are things?"

"If you're here to ask about Alec, I've got a few words for you: go ask him yourself. We're not even close. If you're really that curious, you know you can walk into the Institute and just ask. Or, you know what would be even better? Getting back together with him. Because he's pretty beat up about your dumping him, and, judging from the bags under your eyes, you are too. So just cut the crap and do all of us a favor." Alec being miserable makes Isabelle mad, and so, while Simon doesn't want to be personally invested in a relationship as complicated as Magnus and Alec, he kind of is. A mad Isabelle means less making out and more bad food, all of which he's obligated to eat because, well, that's what boyfriends do.

Magnus shakes his head. "You don't understand. It's not that easy."

"I think it kind of is. Just tell him you made a mistake!"

Magnus stares at Simon with this profound sadness completely out of place on the face of a man who looks so young. "Sally, I can get back together with him all I want, but the problems will still be there." He cocks his head and looks at Simon thoughtfully. "Aren't you dating Isabelle Lightwood now?"

Simon nods.

"I haven't forgotten that Alec and I weren't the only couple who should be experiencing immortality problems. You're young now, so it probably doesn't matter to you yet, but one day you are going to wake up and realize that while the girl you love grows older by the day, you're still stuck at sixteen. So look me in the eye and tell me that is a healthy relationship to fall back into." When Magnus sees that he's struck Simon silent because he hasn't thought about this yet – doesn't want to, he seems contrite. "Simon, all I can tell you is to enjoy it while you can. A couple of years at most. Make the best of them."

It's just Simon's luck that the couple he didn't want to have anything to do with – Malec (as Clary dubbed them) is so much more complex than his mind can handle – would be the one to bring him to reality. Because their only problem isn't just the fact that he's Isabelle Lightwood and he's Simon Lewis, is it? She's going to die one day, and he'll be standing over her grave, his body stubbornly refusing to age.

When Simon and Isabelle meet up on a park bench – because they're slowly turning into that kind of couple – he's mentally exhausted. She twines her leg around his like a cat and lays her head on his shoulder. "So how was your day?"

"Tiring," he says simply.

She smirks. "Have fun asking everyone we know for love advice?"

"How did you know about that?"

"You do realize I actually talk to people, right?" Isabelle rolls her eyes. "If you needed advice, you could have just come to me."

"I can't ask you about…you," he says as if it's the most obvious thing in the world. "That must be going against some law in the universe."

"If you had just asked me, I would have told you that asking any of them for advice is just suicide. I like you because you're a bumbling dork, okay? No amount of advice is going to change that, and I'm perfectly fine with it." She punches him playfully. "Now what exactly did Jordan say about throwing me to the floor and making passionate love to me?"

Simon's face turns red. Not like the rosy-cheeked adorableness of cherubs, either. Like blatantly, stinking fire truck red. "Um, er, uh – "

Isabelle has the decency to interrupt his mumbles. "You're adorable."

"I'm just…afraid this won't last. Not just because we're so difference but because, well, you know…the immortality thing. Magnus and Alec already broke up because of it – how long do you think it'll take us to do the same?"

Isabelle tightens her grip on Simon's shirt. "Not yet, no, we're not talking about that yet. We'll cross that bridge when we get there. But promise me something?"

"Yeah?"

"Don't break up with me like Magnus did Alec. Because honestly, I doubt you have the heart for it, and you'll stumble through it awkwardly until you figure out you don't want to break up with me after all."

Simon laughs. "You think so little of me, Isabelle Lightwood."

And as they're sitting, just sitting there next to each other, Simon thinks that maybe it is cosmic intervention, but maybe she's just Isabelle Lightwood and he's Simon Lewis and their paths are supposed to naturally intertwine without any kind of intervention at all, cosmic or otherwise.

"Simon, tell me a story?" Isabelle asks suddenly.

"What kind?"

"Something about two people who aren't supposed to fall in love who somehow manage to do it anyway."

"You know, I'm pretty sure there are enough Disney movies for me to tell a million of those, but I think I've got a better one." He clears his throat and begins, "Once upon a time, there was a girl named Isabelle who made boys fall in love with her by day and killed demons by night. And then there was Simon, who never had any luck with members of the opposite sex and was kind of, for lack of a better word, a complete and total loser." Isabelle snorts, and Simon thinks he's on the right track. "They didn't even really like each other that much at first – Isabelle was a snob – but, eventually…"

AN: Review?