I'm fairly new to the Adventure Time fandom, and I ship Finnceline so hard you could hear the crack it made in my list of previous shipping priorities; accordingly, since I believe it to be my duty as a fanfiction writer to write at least one fluff fic of the pairings I support, I wrote up this one-shot to analyze how Marceline might wind up with Finn when he's of appropiate age.

And also, fluffiness, character analysis, and more fluffiness. Because every pairing deserves more of those.

Disclaimer: I don't own Adventure Time (Pendleton Ward does, that mad genius) and I make no pretensions to.

...

It's been three years since Marceline met Finn and she considers her investment in him very heavily these days, even though it's not really in her nature to think too much. Reflecting too much on things wastes too much time, which minimizes the amount of fun stuff she could better spend her time doing, but sometime she has to, especially in these recent months after Finn started living with her. Every so often, when her thoughts aren't conflicted and she faces the distasteful task of figuring out what she really wants here, she catches herself thinking why she hadn't noticed Finn growing up right in front of her until it was too late to do more than tease. It's certainly not a bad thing that he's grown up physically, (Not by a long shot, she thinks with a smile she doesn't have the inner duplicity to suppress), but the good aspects are wound up with older worries about precisely this sort of thing and when the worries get too intense, she feels that she just blinked and boom, Finn wasn't a kid anymore but someone to be...interested in, in that particular and very special way that has all sorts of important aspects that get so horribly confusing to think through.

Even so, she has to, because he's still very important to her, and she can't just dismiss the possibilities because they might be inconvenient or uncomfortable. Finn is fun, and now also pretty dang good-looking by her well-honed standards and also her closest friend. She doesn't know she's supposed to put all these things together and still have the world make sense, but she must, she can't just ignore it or pretend it's not there like she does with almost every other problem, and the only kind of force (the kind mixed up with romance and related issues that she knows very well that Finn is still dreadfully naive and inexperienced in), that would be appropriate to the matter, fills her with trepidation outweighed by a surprisingly intense measure of anticipation.

She has to acknowledge the reality of the situation because Finn lives with her now. Strange, when analyzed thoroughly, but quite pleasant once she had adjusted to him being there. He'd moved in after Jake married Lady Rainicorn and she moved into their place and Finn, probably knowing what that meant sooner or later; had moved out. Marceline had plenty of places to spare and they were friends, so he obviously thought she might lend him a house for a while, but she had thought it might be fun to have a roommate, so she offered him a chance to move in with her. Into her home under the highway. It wasn't quite as impulsive as their friends may have thought, and at the time she had thought it had been mostly platonic (and their friends had seen through that self-serving deception; Marceline had become a truly bad liar when it came to Finn).

Finn, naive and nice guy that he was, had accepted, and not too long after she helped him move his stuff into a spare room she had built just a few weeks ago with absolutely no ulterior motives (or she told everyone with a innocent expression she made quite sure everyone saw through), she can't help but rewind her mind back to when she'd moved into Finn's old treehouse with Ash, and it's like everything's reversed for her now; where once there was a self-serving sexist jerk who liked to pretend he was her age, now there's an almost-man who honestly cares for her. One who doesn't care at all how much older she is; beyond thinking that all the stuff she's done is incredibly cool.

Ash, she had realized after he had casually betrayed her, (like so many of the others, a sad and bitter thought remarks), had never really cared about her beyond whatever brief interest he had, based completely on sexuality and attractiveness. Not like the way that Finn cares about her, the way he sometimes just looks at her like she is perfection personified in punkish form, that the moon and the stars dance to her music, and that the sun only burns her because she's so awesome that it can't handle the competition...

It's right thinking, in her opinion, but it's not an egotistical elaboration of something he might think. She knows he thinks that because he told her that once, when she had found out about a plant that some lunatic wearing a sandwich board (and those guys are generally trustworthy, in the land of Ooo) had told her about and distilled it into a red drink that had made her normally loose inhibitions fall apart, and Finn had gotten it even worse, and when he told her that amazingly sappy line (without any of the pretension Ash might have; his line was totally genuine and so she thought it adorable instead of deserving a light smack upside the head). He had blushed and stammered the whole way, several of his missing teeth showing through in a big dumb grin and then he had wavered, like he was going to fall over, and he just looked so vulnerable that she'd succumbed to a sudden impulse and kissed him right on the lips, a short and exceedingly intense lip-aching smooch that stopped with a pop and ended with him on the ground on his back and her still on top of him and kissing him before finally letting him breathe while she was giggling like a total girl (and was't it embarrasing to remember that) and she had been babbling hopelessly like a love-struck idiot, and as soon as he had caught his breath he started doing the exact same thing, and if Jake ever found out about it, he would never let either of them forget it. He'd probably be telling it to their kids-

And that sort of thought always ends in a break, and she wonders (a little embarrased, a little seriously thoughtful in spite of herself and the weird examples of her own parents ) when kids had ever entered into thought about her and Finn. It's a sobering thought, though perhaps not as much as whether or not the kissing had been a minor detail that she is blowing out of importance or that it was a declaration of love from both of them. She doesn't know which is a bigger thing to think about.

She'd blushed really hard then, when she'd kissed him seriously, and it's the first time in a long time Marceline remembers blushing so bright and hard that it had actually hurt. It had been a good hurt, like sunlight cracking through her near-perfect defenses and reminding her of when she had been small and weak and needed someone to take care of her. Perhaps, in ways she doesn't think about much, she does need someone.

Finn broke through a lot of her defenses; around him, she could drop the pretenses and just hang out. It was...relaxing, not having to keep up any illusions of being the monster her enemies were afraid of or the daredevil who didn't ever cry that Marceline had made everyone in Ooo (that even knew about her) believe. She didn't have to be any of those things around Finn, just the rocking lady he knew she was. The last time she had ever been through an emotional catharsis like that was when she'd finally had enough and had banished her father to the Night-O-Sphere, and there had been too many conflicts there for her to live with comfortably, like the sense she'd betrayed the only person she had left (soul-sucking monster of a abomination though her father was). With Finn, there's no issues like that; no awful conflicts, no lingering feelings of regret, no fading sense that she'd somehow broken an unspoken promise with her long-dead mother.

Finn just liked her for who she was; he didn't seem to wonder if her father was an abomination that ate souls, then what did that make his daughter? He didn't care about how she had been desperate enough to date a selfish jerk like Ash. And he didn't make any uncomfortable intrusions into what her life had been like before she'd met him unless Marceline brought it up first, and if she talked to him about it, it wasn't uncomfortable anymore. She thought he wanted to know some of those things, sometimes, saw the unspoken questions lingering in little awkward silences right before his attention shifted and he moved the subject to something he clearly thought was more important.

Some things were better left unspoken, and she was relieved that they were, not that she let him know.

So, over the years, a lot of things had gone unspoken between them. On Finn's side, his own clear longing for answers about what had happened to the rest of the humans (and since Marceline had been around so long, she had to know something), the infrequent thoughts about whether she really was mean or not, and perhaps most uncomfortable for him (and Marceline saw this last one as clear as day, she had been alive too long and known too many people not to see it coming), how many relationships she's been in and gotten hurt over them. The difference, of course, was that other guys had generally thought of Marceline as their's and that she had been encrouched upon. Finn wanted to know who to beat up for hurting Marceline.

(Marcie, he calls her. She's been called a lot of names over her life; she's acknowledged some, liked few, and loved less, but that one is her favorite.)

He's a friend to her, no matter what feelings she harbors, and friends matter to her more than anything. It's why she wanted to reconcile with Bonnibel even after their falling out (and it hurts that she still doesn't remember what she did to make the princess of the Candy Kingdom so angry at her), but she's become miserably used to people she thought were friends abandoning her (or forcing her to abandon them) over slights and fights or because they decide that she's a monster (just like her father, a treacherous thought whispers at times like that), and all too often she pushes them away on purpose. Intimacy is scary, because it hurts worse when things fall apart, and it's all the more terrifying because of how badly she craves it; the part of her that is too much like her father wants blood, but the part of her that's much like Finn makes it clear that she wants friends more than she wants to indulge her predatory compulsions.

And, almost always, they leave. Sometimes she makes them leave for their own good, because the inevitable parting hurts less when it's on her terms and they'll won't get broken up so badly, and sometimes not. But it happens, and it's become a delicate balance over the years, acting like a jerk to drive people away because being alone hurts, but getting her friends hurt is worse (and sometimes she goes for friends for so long that it stops being an act and she does do horrible things like force people out of their home on a technicality, and things get worse until she finds people that show there really are good people in the world still, even so long after the Mushroom Wars tore the world and it's people to shreds), and when the fear of them leaving is worse than any of that, she turns herself into a doormat for the people she loves and who she thinks loves her.

(And yet, she doesn't have to do that with Finn, she thinks sometimes. Sometimes she has to stop him from being the doormat, and it's a welcome change of pace.)

She's done it so long that it aches sometimes, knowing what will happen in advance, but it hurts worse being alone. Marceline decided a long time ago that living forever was awesome and eternity is way too long to mope around complaining about it, but she still hates how the people she cares about just keep dying on her, and making them vampires to stop that from happening, but somehow that always changes her relationships; going from potential peers and friendly rivals to vampires who, by definition, serve her.

Not many people know that most of the vampires of Ooo were turned by Marceline when she decided that she just couldn't bear to let her friends go, only for them to more often than not, turn into monsters that she needed to put down, and almost all the rest turn so subservient or rebellious that whatever prior relationship is lost in the shift, and that hurts worse than when they die and aren't moving around to show to her every day how badly she's screwed them up.

That's the kind of pain that keeps her up some days when she ought to be asleep (though never these days, for some reason that is probably Finn-shaped), strumming tunes so bad and tasteless she can't think about all the wrong she's done to her own friends, not that it helps much; that kind of pain never really goes away. Neither do crushes on younger friends or the lost loves she holds to her heart like stitches keeping wounds shut, no matter how sour they might go. One of the bad parts of being a true immortal is a small degree of changelessness, and some kinds of grief and guilt and similar nasty things all wound up together are so bone-deep she can't bear to let herself stop feeling them even if she could just learn to let go.

(Even so, around Finn and also Jake and Bubblegum and the others, she does learn to let go of old aches and guilts, and the future of her immortal lifespan looks a less gloomy shade of dusk then it seems when these maudlin moods strike her.)

For Marceline, when it comes to Finn, these are the unspoken things she dare not let him know of, and there are others. Like precisely what she meant when she told him that he didn't want to go down a certain road with her. Or why he's hardly ever seen other vampires around in Ooo even though she's their queen. And very certainly what she feels or doesn't feel for him, with all the messy complications that are included in those feelings. She's generally happy that he never tries to get her to speak these things, since she's not sure of the answers herself and she's afraid (astonishing though it is, afraid to her very inhuman core) of how he will react. Sometimes she's mad and thinks that he might not care about her in that way, though that kind of thought is seriously dispelled after she had kissed him and he had kissed back.

And it's a big thorny area anyway because she doesn't really know what she feels for him. Not like she did when he was twelve-going-on-thirteen, when she thought he wanted her for a girlfriend and she was utterly terrified of the onset of all the messy problems and painful uncertainties that might result from that when it would be better to stay friends because he was just so much fun to hang out with, more fun then she'd had in so long and she didn't want to lose that, but now, when she thinks about his upfront insistence he didn't want to date her, she can't help but feel a brief rush of disappointment and, certainly, a desire to see if he's really changed his mind about it or not.

It's confusing, how her feelings have changed only over a few years, but he's grown up enough that there's a vast deal of difference between Finn when she first met him and the Finn that lives in her house. He's still soft and short (she doubts that he will grow particularily tall, certainly not as tall as she generally makes herself), and he adventures with Jake most days and with Marceline when he doesn't (and sometimes even when he does; some people are starting to talk about stuff Finn's down by telling stories about Finn and Jake and Marceline, and Marceline really doesn't know how to feel about becoming a member of a team without her say-so or prior consent, but she doesn't mind that much), but apart from that, the changes catch her by surprise every so often. That he's become apparently mature enough to let go of his crush on Bonnibel and 'settle' for being one of her closest friends is perhaps the most apparent.

There are times when she wonders how she has become such good friends (and perhaps more than that) with Finn, when so many of her relationships have fallen through or gone sour or simply drifted away. She thinks, with a faint smirk, that it's because she's approached her relationship with Finn from a position of superiority and power; she made it clear from the begining that she is vastly more powerful then him, older and more experienced dozens of times over and over. Where he makes do with sheer bravado, determination and a degree of absurd strength, she powers through obstacles with the power due to her as the most powerful vampire in existence (she must be, to remain Queen) and a similar degree of bravado.

It's fairly clear that the only reason Finn and Jake survived their initially antagonistic encounter with her was because they impressed her, as much as that event is unpleasant for her to remember. When her other relationships went sour, it was often because in making them vampires Marceline had made them her subordinates, unthinkingly or hoping they could get over it, or when they realized just how much more terrifyingly powerful she was with them. With Finn, it's never a concern because he knew just how greater she was when they first met, and aside from initially being scared witless of her (extremely briefly), he's never been bothered about it. Any change in their relationship wouldn't be effected by this essential difference in age and power, and it's strangely comforting to know that there's some solid ground between them, an inviolable territory that she can be absolutely sure about.

Because there's a lot more things she's not sure about it anymore, as much as that thrills her sometimes. There are times when she looks around and becomes surprised at the other person in her home, her heart starting to beat again in utter shock that she has dared to risk this much, knowing just how badly this sort of thing always goes...and then she remembers that Finn's a particular sort of person, that hero who caught onto her games and told her that she was one of his best friends in the world (through song, no less). And then she sees Finn and realizes he's not the same silly little boy she had come to view with a considerable degree of affection but he's become a slightly less silly young man. A young man who was still essentially the Finn she had known and loved, still slaying evil because it was fun and because it was right, grown up but exactly as much a good person as he had been when she first met him and now grown ever more significant in her personal estimation.

It's not that big a deal, she tells herself and trying to convince herself that she's not lying to herself. That her feelings haven't changed that much, that she hasn't grown so close to him that thought of him leaving her makes her scared to the bone, that hanging out with him fills her brain up with soft fuzzy thoughts and fuzzier impulses that she's reluctant (and still wants so very badly) to act on.

Marceline feels sure, all the same, that Finn's feelings towards her have changed, that perhaps he's rethought his position on her desirability as a girlfriend. (And if he hadn't, she'd probably feel insulted, a dangerous position to take.) She catches herself wanting him to, and as much as the idea of him outright asking her to be his girlfriend scares her, it still makes her think about how much fun it would be. Fun is pretty much the only thing Marceline really cares about as a motivation now, and everyone who knows her also knows this, but they don't know that as the centuries have gone by, all desirable motivations have blended into her unique definitions of fun. Making her friends happy is fun, doing right by her subjects is fun, messing with people's heads is fun, and having someone that loves her and wants to hang out with her is the very best fun of all.

Sometimes the intensity of her own feelings make her want to start being mushy about it and that bothers her a little; she's Marceline the Vampire Queen, rightfully reckoned ultimate badass of Ooo, and she just doesn't do warm and fuzzy, or at least that's what people should be thinking. (Her own people know she does, but that's expected; vampires know that the good of their kind are almost universally big fluffy puppies with bad teeth when they care for someone. Or they're irredeemable psychopaths, but Marceline had killed all those vampires a long time ago.) Sometimes the feelings take an intense turn that outright scare her, such as when she's sitting on the couch with Finn watching old movies (mostly it's the cool ones where stuff blows up and people yell a lot, other times they watch disgustingly mushy romance movies precisely because they're so stupid and the two of them can make fun of them the whole time) and she realizes that he's sitting right next to her, soft and pale and squishy while her continually growing feelings surge together with predatory instinct into something she hates, and then she can nearly hear his heart pumping his blood through his all-too fragile body, an ocean of red moving right there for her to take and she can feel her teeth itch with the compulsion to just attack right there, sink her teeth into the slim rise of muscle connecting shoulder to neck and drink deep, taking all of his essence directly into her and consume it whole, take for her own everything about him there is and ever will be, drinking down his very soul-

Those moments pass fairly quickly, since she's learned to plan ahead and always has something red to drain that isn't Finn, and the compulsion is satiated. (Focused on the movies, Finn never notices. Good boy, she thinks.) Marceline learned how to drain the color red for a reason, with all the mortal friends she's known, and always having something red on hand gets a little expensive in times to come, but it's a reasonable expense, with Finn at risk.

She had told him she was dangerous. She'd told him he didn't want to go down this road with her, but here they are all the same. She's almost certainly brought him down that road, perhaps without his knowing it, but it's happened. She's disturbed sometimes, but feels that it's worth it all the same.

Sometimes she hopes he does harbor some kinds of expectations like she's feeling for him, and she doesn't know how to be certain about it without potentially wrecking everything, so she kisses him every now and then, like she did when he was younger. It didn't mean much more than simple affection then (at least she doesn't think it did, but her feelings have never been very clear to her even in the best of times), and it's still almost always on the cheek or his forehead, and things have changed all the same because it fills her up with a soft thrill while heat swells under her skin like the most delicious unexpected flavor.

She doesn't blush, not most of the time. She's tried to get too used to kissing him to have her body betray her emotions in that specific way, but it doesn't always work out that way. Finn does almost every time, though, and she thinks that this confirms her half-fearful half-hoping suspicions. He blushes so brightly even when she goes into his room after he's been asleep for a while and she's still trying to get a handle on this rather welcome alteration in her domain until finally she floats over to him and kisses him lightly on the lips, so brief and softly that it's like flying into a pink fog less than an inch thick.

Those moments feel...right. They feel good and perfect and other lovely things Marceline hasn't applied to her life in a long time, and the fear of losing him to the vagaries of her fears or time stealing him away from her are fading away, like a dread monster bleeding out in a ancient desert with flowers sprouting wherever it's blood falls.

So Marceline comes to realize that some things - the really important things - don't need to be spoken, and they haven't needed to for a long time. These days now are precious to her, and the dread possibilites that she has always felt so harshly just don't seem to matter anymore, or don't feel like they apply to Finn in the least.

It's a good thought. Good like being around Finn, who's so bright and cheerful and nice that it's like having her own sun that won't burn her. With him, there are no concerns, no buried worries about the futures, no second-guessing or self-doubt. There's just the joy of having fun with him all the time, the prospect of thrills to come, and the deeper joy of knowing that this is far from immaterial or transient.

One day, sitting on the couch (her old one that was unsuitable to non-floating people long since replaced) with Finn with her arm around his shoulder and one hand running clawlike fingers through his hair, a dreamy smile on his face as his comprehension of what else is happening openly slipping away while the swell of her arm brushes against his cheek to send a warm and happy blush on his face that puts shockwaves of pleasant heat up her arm, she realizes that none of the old problems apply to her and Finn. They merely are what they are, simple and obvious and good (so very much like Finn himself, and the first genuinely good thing she's let herself feel in much too long) and the knowing of it makes her grin like a mad fool.

Crazy can be a good thing, she thinks. It's crazy to think that she wants this. But she does, and so crazy she must be. She can live with it.

So, pulling him closer to her with absolutely no resistence from him (in fact, a kind of shy eagerness), she thinks 'MINE MINE MINE' in thoughts that nearly scream themselves through ever fiber of her being, wondering in a happily off-kilter way what Finn would look like with a proper 'M' somewhere on his body (the mark that all things that are truly and perfectly hers have) and just holds him, using her superior leverage to have their lips meet firm and warmly. He does not protest, get upset or anything more than a bit surprised that she has apparently rescinded her years-previous insistence that they would never date, and a soft haze falls about her thoughts, and the feeling that this is right and good and the most correct thing she's done since she banished her father to the Night-O-Sphere.

She tells Finn, without the slightest trace of irony or her usual sarcastic demeanor, "You're wonderful." She means it, as much as she means the most important things she's ever said, and tenses slightly at the traitorous blush warming her face. Finn just hugs her tightly and she dismisses her last lingering shreds of reluctance and hold him even tighter.

It occurs to her that when they had first met, Finn had said the same thing to her. The specific reasons why they had both said them had gone unspoken, given the degrees they had impressed each other at their respective times, but perhaps those were just more things that didn't need to be spoken.