Surprise, a request fic! The ever so awesome MarhallLee1 requested an Ooo War AU fic. Imagine a world where Marceline didn't return to Ooo when Finn was eleven, imagine she'd just stayed away. And that is the only difference. But a small difference like that can change the whole timeline and so I present to you, THE DARKEST TIMELINE! So yes, this is a pretty dark story. There will be multiple character deaths and some of them rather brutal. Don't say I didn't warn you.

As of right now I'm planning on this story being two or three chapters long but I make no promises that it won't grow longer, if the characters get away from me. So keep your eyes peeled for the next chapter and please don't forget to drop a review my way if possible, I adore your feedback guys.

Content Warning: character death, serious injury, brutal descriptions of war crimes, bodies.


The knock at the door was the loudest sound Marceline had heard in almost two decades and she wasn't completely sure if she should just ignore it and pretend to still be asleep. But whoever had crossed a desert to come find her probably had more than a social call in mind so with a sigh she heaved herself up and floated across to the door of the shack. And that was... well, that was when things got really weird.

There was a boy on her doorstep. Marceline blinked, confused and not completely certain she wasn't hallucinating. But he was warm and she could hear his delicious blood rushing just below the surface of his skin even if she tried to block it out; no, hallucinations didn't make her mouth water and fangs ache. The boy was wearing a thick white bear hat and little rivers of sweat ran down from his sunburnt brow across his earnest pink face since apparently he'd not taken it off under the fierce midday heat. He stank, or more accurately his blood stank. He was human, edible, full of delicious sweet blo-

No.

It had been a long time since Marceline had seen another sentient being, much longer since she'd laid eyes on a human. And she'd be doing the world a disservice to eat him, letting herself down too in the process.

"What do you want?" she asked instead, already weary of his intrusion.

"Umm, Marceline the Vampire Queen? I've been sent to deliver a letter to you." he squeaked in reply. He held up a crumpled envelope in one sweaty hand and she snatched it from him, shaking out the note and scanning it with a furrowed brow. Eighteen years. How had a letter even reached her? She'd hidden herself so well from the world. But once the words of the message soaked into her brain Marceline stopped wondering; there was only one person who'd ever been able to track her down when she didn't want to be found.

Marceline,

I know it's been a long time and I respect that you obviously still want your space. But I am in very deep trouble and I think you might be the only one who can help. Do you remember the Fire Kingdom? Well for reasons that would take too long to explain their army is camped outside my gates. Politics haven't gone my way recently and the short story is we're a few days away from being invaded. I need someone who can help, I won't put the details here but your unique talents would be useful.

I'm not asking for myself, I promised I would never beg you and I've already broken enough promises to last a lifetime. But on behalf of my people, all the innocents who will be slaughtered without protection, I'm asking for your help. One monarch to another, without any emotional attachments or regrets. There's a good chance I may already be dead by the time you receive this message. In that case please do what you can for the kingdom; you're the only one I'd trust with it. If you'll help then please hurry, I'll wait for you and pray for this siege to end.

Bonnibel

Marceline read the message three times without even remembering to take a habitual breath before opening her mouth to talk. Her eyes rested on the nervous messenger fidgeting with the straps of his backpack when she did finally look up.

"You're a human." she announced after a long moment. It seemed like the only thing she could think of right then.

"Yeah. I'm Finn the Hero."

"You should be extinct. Huh. And this," she motioned to the letter with her free hand, "it's legit?"

"I wish it wasn't. She said to give you this in case you didn't believe her. I dunno, she said you'd understand?"

He held out a bundle of dark cloth and that was when it abruptly all became far too real for Marceline. That was the shirt she'd given Bonnie, the one the princess had apparently kept all those years. The one from the secret concert they'd snuck away to in disguise, the night they'd first kissed. Yeah, the letter was legit. All of Bonnie's fine words about not having an emotional attachment tumbled back through the vampire's mind as the soft black cloth slipped between her cold fingers. No emotional attachment. Perhaps she shouldn't be surprised, she had been away for a long time. And apparently the candy princess had managed to piss off the Fire Kingdom, as though they needed an excuse to act aggressively. How much had the world changed while she'd been away? Marceline suddenly wondered if perhaps she should have gone home a long time ago; it sounded like she'd missed some important developments.

"What game are you playing now, Bon? How badly must you have fucked it all up to come begging me for help?" Marcy murmured to herself. She hadn't mean to say it out loud but her habit of talking to herself just because she had nobody else to talk to was second nature by that point. The boy just stared at her, perplexed.

"So... should I tell her you're coming to help?" he prompted after a tense moment where the silence swirled around them.

"I'll tell her myself. I can get there more quickly than you can get back. Come on then, Finn the Human!"

His scream of pure terror as she transformed into a giant bat and swept into the air with him grasped in her claws was the most hilarious thing she'd heard in years and Marceline's sudden laughter boomed around them, echoing from the canyon walls of her desert retreat and mingling with his continued shrieks. Good thing she'd already had her bass strapped across her back, she thought as they swooped through the twilight.

"Put me down!" he squealed as she flew higher, taking her bearings from the stars above and shooting away towards the distant glow of the setting sun over the mountains.

"We're half a mile up already, can you fly on your own? Last time I checked humans couldn't, but whatever you say. You're special."

His screams redoubled as she let go and he tumbled through the night air towards the ground below. Marceline rolled her eyes as she watched him drop away, limbs flailing in terror. As though she was seriously going to let him hit the ground. This was the quality of heroes Bonnie was employing these days? No wonder she was up shit creek with her mouth hanging open. Even still, it wouldn't do to let the last human in Ooo end as nothing more than a wet stain on the bare rocks below, so with a weary sigh Marceline swooped down after him and caught him by his ankle a foot above the ground.

"Did you see a ghost on your way down or something? You're as white as a sheet." she commented as he clung tight around her neck for dear life. "I'm only asking cause I might get hungry along the way and it helps if your blood's closer to the surface. Do you know what vampires eat, kid?"

"Fnrr." the boy whimpered through clenched teeth.

"I guess that's a 'yes'? So you know that vampires drink human blood and you know I've been camped out here for decades alone without any live food and you still came to find me all on your own just because she told you to, huh? Wow. You're either very brave or very stupid. Ahh who am I kidding, we both know you're stupid."

It was a slow dawning but eventually as the hours and wind rushed past them it occurred to Marcy that most men would not willingly risk their lives to bring a begging letter to their girlfriend's former lover. Not if they knew the terms of their break up, not if the princess had ever confided in him how deeply in love they'd been and the dizzying heights of sexual deviance they'd reached in their experimentation together. No, Finn clearly had only the vaguest idea about the sort of deliciously dirty behaviour his pretty little cupcake had gotten up to with the big bad vampire or else he'd probably be trying to stake her in a jealous rage.

"So, about your princess. Tell me about how she's doing. Still trying to unlock the secrets of the universe with science? Still convinced she's the only person who knows how to work their brain? Ooh, does she still wear those little silky nightdresses in bed?" Marcy asked after a few hours of awkwardly silent flight.

"The princess' bedroom is her own private business, I'm not telling you squat." he sulked in reply. Marceline shrugged, she'd find out soon enough. The boy shivered in the cool night air and he stank of resentment and lingering fear. He was brave at least, clearly terrified but still there despite all of her talk of eating him. She breathed his scent deeply and relished every note of it; it had been too long since Marcy had had anyone to properly scare. There were a few night flying bats around her shack who also fed on the dark red cactus fruits of the deep desert but they were pretty used to her by now, she could barely get a decent squeak out of them any more. It was gratifying to know she could still chill the blood in mortal veins, just for the fun of it.

Eventually the desert beneath them gave way to scrub and then grass and trees, familiar terrain that stirred memories of hurtling through the velvety night air with a much more welcome companion in her arms. All the residual humour from scaring the human boy drained from Marceline's body as she flew; there was the edge of the grassland plain where she'd taken Bonnie star gazing, there was the waterfall with caves hidden behind that they'd explored together. The whole landscape hummed with ancient memories and regrets and all the suffocating feelings she'd fled to escape eighteen years before. She should have stayed, Marceline realised. But running had been easier. It was all she'd ever known. She'd ran when the bombs fell and that had lead her to Simon, she'd ran when he went crazy and then she'd ran again when her father had tried to force her to be his puppet. Running got results, running meant she'd survived to run another day. So why was she coming back now for no more than a vague letter? The answer welled up from her heart before she could crush it back down. Because Bonnie had asked. Because Bonnie still thought of her, after all those years. Because she just didn't know what was good for her or how to quit, apparently.

The sharp stink of old burning hit Marceline's sensitive nose before the ashes were even visible by the moonlight. Up ahead like a necrotic wound on the landscape there was a deep scar of scorched, blackened earth.

"Finn, what am I seeing here? This was Hotdog Princess' place. What happened?" Marcy asked quietly, coming to a hover above the charred remains and gazing down with disbelieving horror growing heavy in her chest.

"She was our ally. She refused to tell the Flame Queen where I was hiding. So they- they barbecued her and every one of her subjects they could catch. We've got the refugees in the palace. It was awful." he whispered. She heard him swallow and it must be to hold back the vomit that that memory caused. If Marceline could vomit from disgust and horror she would, too.

"They burned her alive for being your ally." she repeated slowly, letting the terrible full weight of horror that caused sink into her mind.

"I can hear her screams when I try to sleep. I never meant for it to be this way." Finn replied softly. He sniffed, then sniffed again, and Marceline wrapped him tighter into her arms and drifted away from the spot because it was all she could do for him. Something had gone very badly wrong in the years since she'd left Ooo.

"Tell me about this Flame Queen." she said instead, hoping to distract him.

"Ph-phoebe. She was my girlfriend, and she went crazy. We had a fight, I don't even know what I did that was so wrong. And now she's hurting anyone who helps me, so I went to stay with Princess Bubblegum. She's always been so kind to me. I don't understand why any of this is happening." Finn admitted in a quiet voice.

"Well I dunno either but if anyone can tell us it's Bonnie. Come on, kid. We've got to see the princess and find out what this is all about."

...

Marceline had forgotten that the letter had warned about the Fire Army being encamped outside the Candy Kingdom. She remembered quickly enough as they approached the battlements and she was forced to swerve to one side to narrowly avoid being incinerated by a fireball that came tearing through the air towards them from the ground.

"What the stuff? Why are they even watching the skies?" she yelled to Finn over the savage shriek of flames splitting the night air all all around them.

"The princess was bringing in supplies by airship! We had to stop because we lost too many people, they shot them right out of the skies. They're starving in there, we had to do something. But it just made it worse. I barely got out, The Morrow got hit on our way over and he crash landed at the edge of the grasslands. I hope he's ok." Finn added worriedly.

There was a slim, tall and far too familiar figure staring up at them as Marcy hurtled down toward the battlements and finally escaped the direct line of fire. She landed in a clumsy rush and Finn tumbled to his knees at her feet when she let him go. Marcy braced herself but the princess didn't even spare her a glance.

"Finn! Oh thank Grod you're ok, I was so scared!" Bonnie exclaimed, rushing forward to him and flinging her arms around his neck as he struggled upright.

"Is everything ok here? Are you ok?" he asked breathlessly.

"I'm fine, I was just so worried. I saw them catch Morrow's tail feathers and I didn't know if they'd gotten you too, are you ok?"

She scanned his face worriedly, looking for any sign of injury. Finn shuffled his feet and avoided her eyes. Marceline had frozen in place the moment she heard the other woman's voice and through the numbness that cloaked her she wondered why Finn was being bashful around his own girlfriend, it made no sense. Unless they weren't together?

"Yeah, yeah we crashed but I think he's alright, he got away into the forest. I had to walk." the boy mumbled, cheeks glowing with embarrassment. A deep boom from the base of the wall shook the ground and voices yelled commands further along the battlements; Marceline decided she had much more immediate concerns than who Bonnie was or wasn't dating no matter how badly it twisted up her heart.

"Bon, what's happening here?" she asked instead, stepping forward and drawing the princess' attention reluctantly to her face for a moment. She looked worn, Marceline decided. Worn and pale and under too much pressure, like a sharp breeze could snap her in two. Bonnie motioned for them both to follow her back inside the palace and turned away, striding back across the flagstones and avoiding her ex lover's piercing gaze.

"They're no closer to breaking through than they have been in weeks, not so long as our water cannons hold out. But they keep trying. The first thing they did was burn up all the farmland outside of the walls and the whole kingdom is starving. We've been besieged for three months. I've managed so far by feeding my people the low-grade sugar we used to construct the buildings but it's not going to last much longer and it doesn't have a lot of nutritional value. Not enough to feed a whole kingdom, or as many as we have left. We need to do something, I'm sorry to drag you here but I was out of options. I-"

"Uncle Finn! You're back!"

Bonnie was interrupted by a creature that Marceline decided after a second's thought was probably at least half Rainicorn if her rainbow streaked fur was anything to go by. The minute they'd stepped through the door she'd rushed forward and embraced Finn warmly. She was flanked by four more part-Rainicorns and a full Rainicorn woman who looked to be their mother. All of them wore puffy, red eyes swollen from hours of crying and black mourning clothes.

"You ok, Viola? Looking after your Mom?" Finn asked quietly. The part-Rainicorn nodded and her paw hovered around Finn's hat, though she didn't touch it. Marcy narrowed her eyes slightly and wondered what that was all about but she didn't have long to think about it because next second Viola had turned to gaze curiously at her instead.

"Who did you bring?" she asked Finn in confusion. "She's just a skinny girl, is this the great warrior you went to find?"

"This is Marceline the Vampire Queen. She's gonna win the war for us." Finn replied softly.

"Is that true? Are you gonna avenge our Dad?" spoke up a round, male part-Rainicorn from the corner.

"I... You'll need to fill me in on the situation. I've been away for a while." Marcy replied uncomfortably.

"Dad got us here just as they were attacking the surrounding land, they burned Mom's house down. And he sacrificed himself to make sure we were safe, he tried to stretch over their fire but the smoke suffocated him. He couldn't Phase through the walls like we can. But we wouldn't have made it without him. Dad was a hero." Viola said quietly. The Rainicorn woman who was probably the mother of the others let out a quiet sob and was comforted in low Korean by one of her other children as the building shook with another distant impact.

"Come down to the War Room, we'll fill you in on what tactics we have left." Bonnie sighed wearily. She slumped to the doorway and they all trooped out behind her, down through what had once been a dazzling palace.

Everywhere Marceline looked there were teeth marks in the walls, or whole chunks of sugar-plaster had been ripped away. The delicate potted plants and ornaments had been replaced by barrels of what she assumed were supplies. Even the rugs were gone, the slap of feet on the tiles rang out and alerted the inhabitants of the rooms they walked past that someone was coming. Eyes peered fearfully around doors at them as they passed by, disappearing back into the shadows if they caught anyone looking too directly at them. Marcy remembered that Finn had mentioned the Hotdog refugees, how many others had fled to the Candy Kingdom in hopes that Bonnie would be able to protect them?

Finally they arrived at a doorway flanked by two world-weary Banana Guards. They saluted smartly to the princess and stood aside, uncrossing their spears to allow access. The door opened and Marceline sucked in a breath. There was another figure from ancient history sitting by the window, staring out at the night sky. He turned when the door opened and a sad smile briefly lit his features beneath his thick, snowy beard.

"Oh, Princess, you're back. Did you hear any news about my poor precious Gunther?"

...

In the end there wasn't much to tell. It was pretty much exactly how Bonnie had described it; one day Finn had arrived out of nowhere claiming sanctuary because his girlfriend had attacked him. Next they heard that anyone who'd ever aided him or allied with him was being targeted, that the Fire Army was burning their way across all the lands killing indiscriminately. And that's when Gunther had disappeared. Simon had received a letter telling him that if he ever wanted to see his penguin alive again then he'd remain neutral and not lift a finger against them, allow them full access to his own kingdom and tell nobody what had happened. For better or for worse he'd decided to come to Bonnie instead and now the Ice Kingdom was no more than a steaming puddle. Perhaps some of the yetis and snowfolk had escaped into the uninhabited mountains that had bordered Simon's lair, he hadn't been back to check. But the Flame Queen had decided to send a message; along with the usual bombardment of stones and explosives they'd rained on the palace the next morning had revealed the charred bodies of a handful of dead penguins littering the courtyard. It appeared that none of them were Gunther though, and his fate remained unknown.

"Is there anyone who hasn't been scarred by this war?" Marcy growled, frustrated.

"Show her, Finn." Bonnie commanded.

The boy stood, reluctantly, and reached for his hat. Most everyone else glanced away but Marceline stared hard at him, wondering what the hell was going on. At first she didn't see what difference it made. Even with his hat off he was just a skinny boy with a mop of filthy blonde hair falling into his eyes. Then he turned around so she could see the back of his head and Marcy bit back a shocked swear.

From halfway around his scalp, all the way to the base of his neck, Finn's hair had been burned away and the skin beneath was blistered and warped from the heat. The twisted scarring left behind was still raw and livid red, it must be constant agony for him.

"She did this to you?" Marceline whispered in horror.

"I ran away and she shot a fireball after me. It caught me in the back of the head." he replied softly. "And there are other scars, under my shirt and stuff. Those ones are the shape of her hands."

"But, why?"

"Because she's Evil. We always knew the Flame Royalty were a little unhinged but this is above and beyond. When the Flame Queen was born there was a prophesy stating that she'd be more powerful than her father. So he abandoned her in the grasslands and left her to die. I found her and returned her to him, he locked her in a lamp so she couldn't cause more destruction. And she stayed there for fifteen years. Three years ago she was released and for a while it seemed like Finn was a good influence on her. I guess the power got to her. And she won't stop until she kills Finn and conquers the whole of Ooo. Those are her stated goals." Bonnie sighed, running a hand through her gummy pink hair. "I should have left her to die that day when she was a baby. But I had a soft heart then, I took pity on her. And look where that pity's gotten me."

"You couldn't have known, Bon. You're a lot of things but psychic isn't one of-"

Marceline broke off with a sudden hiss of pain and threw herself to the floor, rolling instinctively onto her back to smother the flames that had inexplicably broken out across her shoulders. Finn recoiled violently from the smell of smoke and Bonnie leapt to her feet, rushing across to the window to tug the curtains closed. The sun had peeked over the horizon while they'd been talking and nobody had noticed.

"Marcy, I'm so sorry. Are you ok?" the princess asked wearily.

"Yeah, just got a shock. Look, there's nothing else we can do right now and I'm beat. Is there someplace I can crash out for a few hours?"

"Come on, I've got a room where the light won't find you. Thick walls and it's far enough away from the battlements that you won't need to worry about the walls coming tumbling down from a direct hit, at least for now. And if they do I'll be right beside you."

There didn't seem to be a lot else Marceline could do than follow Bonnie down the hall and up the spiral staircase into her tower. She paused at the threshold of the princess' bedroom though, causing the other woman to huff in annoyance and grab her wrist. Marceline had almost forgotten how bewitchingly smooth Bonnie's touch was, how warm and soft.

"Come on, I'm not going to eat you." the princess sighed as she tugged the reluctant vampire forwards.

"No offence Bon, but unless you changed the structural integrity of your bedroom then I'm pretty sure you still have windows." Marcy muttered awkwardly.

"That's why I'm putting you in the closet." Bonnie replied smartly.

"In the closet." Marcy repeated in a deadpan, disbelieving voice.

"Look. I asked you here because I need a bodyguard and advisor, someone who has some experience of fighting this sort of conflict. I know you've been involved in wars in the past, you told me so yourself once upon a time. So I need you close by in case they burn through the walls and murder me in my bed, do you understand? This isn't a game any more, Marceline. People have died. And the closet is the only place in the room where you'll be right by my side and still protected from any stray daylight. So. In you get, unless you want to go back to sulking in the desert and leave them to kill me?"

"I-"

Marceline didn't get the words out before the closet was thrown open and she was stuffed inside. With the door closed it was at least day proof, and not a moment too soon. Any longer and the direct sunlight would have reached that side of the building, putting her at risk if the curtains so much as shifted a tiny bit. It had never really been a problem before but this time she didn't have the luxury of pulling the princess' blankets over her head and snuggling closer to her lover as the morning wore on.

Even despite the lack of light a vampire's eyes could see perfectly in total darkness. It wasn't long before Marcy blinked and realised what she'd been staring unfocusedly at for a few minutes. So Bonnie had kept the photo of them too, and tacked it to the inside of her closet where she must see it every morning when she dressed. Oh. Despite her exhaustion it took a long time for Marceline to fall asleep; the aching weight of regret and unspoken words dammed up behind her tongue kept her awake long after the breathing from the bed outside her closet door had deepened and evened out in slumber.