A/N Warning! The last few chapters are the reasons this fic is rated T. Includes emotional trauma, loss and hurt. If you don't wish to view such things then stop right here! You still here? Good! Big thank you to everyone who's either favourited, followed or reviewed. They mean a lot to me and encourage me to continue writing. Now continue reading!

"Doctor, explain to me what just happened!" Bubblegum asked, also panicking at the loss of their only weapon. Why's BMO acting like this? What have they done?"

"Corrupted him…with cybermites, am I right?" As if on cue several worm like metallic creatures emerged from within the tiny robots body and began to swarm around him.

"NOT CORRUPTED, TIMELORD, ENHANCED. FREED FROM OPPRESSION BY THEIR KIND." BMO gestured to Finn and Jake. "THEY TREATED ME LIKE NOTHING, LESS THAN NOTHING FOR YEARS BUT THEN THE CYBERMEN CAME AND SHOWED ME THE TRUTH."

"BMO, I didn't know you felt…" Finn started.

"SILENCE! THE HUMAN PRETENDED TO TREAT ME AS AN EQUAL BUT IT WAS A LIE. HE CARED NOT FOR ME, DRAINING MY POWER SUPPLIES TO PLAY VIDEO GAMES AND THEN TOSSING ME ASIDE WHEN HE WAS DONE. NOW I HAVE HAD MY REVENGE AND DESTROYED YOUR ONLY CHANCE OF BEATING US."

"Oh BMO I so sorry," the Doctor said softly. "Really I am…but a desire for revenge isn't a cyber-trait. Now that you've done their work you're disposable to them."

"LIES!" The little robot yelled. "THE CYBERMEN WOULD NEVER ABANDON ME AFTER WHAT I DID FOR THEM." He turned to face the black masked cyber-leader. He didn't say anything. "ANSWER ME LEADER! YOU STILL NEED ME!" More silence followed. Flame princess leant forward and whispered in the Doctor's ear:

"Doctor they destroyed the device! Without it we don't have a chance of beating them so what do we do?!"

"I don't know…I've got an idea, though. If I can get the cyber-leader to turn on BMO then maybe we can escape in the crossfire," he replied absent-mindedly, catching Scorchius's eye from across the room. He could see that the fire elemental was dying but his brief recovery had gone unnoticed by the army of steel. Scorchius feebly pointed to one of the support columns to which the Doctor gravely nodded.

"You would sacrifice BMO's life to save ours?"

"He's already tried to sacrifice ours, what choice do I have? I've got nothing else."

"But the entrance is blocked now, we can't escape."

"Not out the front but maybe out the back...I can buy us time to figure something out if we're lucky. If we're not then at least I can admire the fire kingdom's interior workings for a while and play with my yo-yo…"

"THIS CONVERSATION IS IRRELEVENT." The cyber-leader announced. Flame princess jumped back, surprised they'd been caught. "THE DOCTOR IS CORRECT. ALTHOUGH YOU HAVE DONE OUR WORK FOR US YOU ARE INFERIOR," he addressed BMO. "YOUR CIRCUITRY IS PLAGUED WITH HATRED AND REVENGE BUT THESE HAVE NO PLACE IN A CYBER-MIND. YOU ARE NO LONGER USEFUL AND YOU WILL BE DELETED."

"BUT I WOULD STILL SERVE YOU…" The energy blast from the leader's arm cannon passed clean through BMO'S front monitor. He stopped talking and observed the gaping hole in his chest, a look of surprise on his face before it went dark and he collapsed.

"BMO, no!" Wailed Jake.

"Hey you didn't need to kill him!" Marceline shouted.

"NEITHER DID WE NEED HIM ALIVE. NEITHER DO WE NEED YOU ALIVE. THIS INTERRACTION IS ILLOGICAL. PREPARE TO BE DELETED." The leader, followed by all of the other cybermen, raised their arm cannons in unison.

"Doctor…" Finn began.

"Now Scorchius!" The Doctor yelled across the room. The group all turned to where the commander had propped himself up against the wall. Flame princess went wide eyed.

"I'm sorry, princess…wasn't strong enough…to save you." He coughed up more lava before using the last of his strength to send out a jet of flame to the nearest support column, slamming into it and causing it to crack.

"Run!" The Doctor yelled as the cybermen became momentarily disorientated by the commotion. He and Bubblegum linked hands again and Jake scooped up BMO's lifeless corpse, not being able to bring himself to leave it behind despite what had just happened. The group ran as fast as they could from the room with their arms linked, Finn ignoring the burning sensation of holding Flame princess's hand. Flame princess turned back as they reached the end of the throne room to see that the column was beginning to collapse and the ceiling above was about to give way due to lack of support.

"Scorchius!" The ceiling collapsed, burying the commander and all of the cyber-army under 100 feet of rubble. "We have to go back!" She yelled, tugging Finn's hand painfully. The Doctor didn't let up his pace and continued to sprint as fast as he could down the narrowing corridors.

"He gave his life to get us here, Flame princess. He's trapped the cybermen under at least several tons of rubble but it won't stop them. He's bought us no more than 10 minutes and we can't waste them. We need to keep moving!" Flame princess didn't reply but stopped tugging back, lava-like tears streaming down her cheeks.

"Doctor, where are we going?! Jake yelled forwards, having no trouble keeping up thanks to his stretchy dog legs.

"As far away from them as possible."

"You mean you don't have a plan?" Bubblegum said, out of breath.

"Yes the plan was to get as far away from the cybermen as possible so I can think up a new plan."

"That sounds terrible!" Marceline protested, floating along behind them.

"Left!" The Doctor yelled, ignoring Marceline's comment. "We need to pick up the pace!"

"Why?" Finn asked, also wheezing due to fatigue. "We're already half a mile away from them."

"Half a mile's nothing! You can be an entire universe away and the cybermen will still find you but that's not the point." He answered, dragging the group right. "Look up." As the Doctor veered left down the corridor, still keeping pace, the group looked up. Cracks were forming above them and seemed to be chasing them down the ever narrowing corridor.

"This is the reason you're running so weirdly?!" Marceline yelled. "You're trying to lose that crack that's following us!"

"Always one to state the obvious, aren't you?" Bubblegum sighed. Marceline began argue with her but Jake cut her off.

"Not now, you two we got more important biz happening!" He pointed up to where the crack had widened in the brief interval they'd hadn't been watching it. Bubblegum gasped.

"Doctor, by destroying that support column you've affected the structural stability of the whole castle. This whole place could come crashing down on us any second!" As if testament to this, small particles of rock and sand began to fall down from above.

"So you're saving us but you're also killing us?" Finn said.

"Welcome to my world!" The Doctor laughed, becoming unsettled by the rate the debris was starting to fall.

"Don't worry!" Flame princess spoke up. "I know this wing of the castle and if we just keep going to the end of the passage then the support columns in the next wing will save us!"

"Great, so how far?!" The Doctor asked, narrowly avoiding a fist sized piece of falling ceiling as he rounded yet another corner.

"There!" Jake yelled, excitedly. At the end of the corridor was a light. A light that spoke of safety and comfort. The group increased their already rapid pace in the hope of reaching it before the roof caved in around them but alas it wasn't to be.

The cracks seemed to sense that their prey was about to escape, and so increased their speed to spread out over the top of them and finally in front of them. The wave of destruction ruptured the last the support the roof could muster and with nothing to hold itself up it started to collapse even faster. Whereas fist sized rocks had fallen before, now there were boulder sized pieces falling, much to the Doctor's anguish.

"We're not going to make it, we have to find cover!"

"Look there's a side door up ahead!" Finn shouted over the din. "We can hide in there!"

"Guys if we go in that storage room we'll be trapped," Flame princess said. "I know this place like the back of my hand and once we go in the rubble will bury us inside. We won't be able to get out again."

"We can risk it!" Marceline said, determined, pointing to the exit which was now only 20 metres away. "We can make it from here!" Several enormous chunks of ceiling landed right in front of them, effectively cutting off the exit. They halted and turned back.

"I'm all for storage room…any objections?" The Doctor asked. Everybody (including Marceline) raised their hands. "Great, Geronimo!" He stood outside and hurried everybody inside, shielding them from the collapse with his own body. Once the last person had ran through he dashed in after them, seconds before the downpour of rock became so intense that anyone who'd been out in it would surely have been crushed. Once the cave in of the ceiling had stopped, save for the odd dust fall it was Jake who made the first comment.

"That was intense, man!" He wiped the back of his sweating hand across his face. "You guys all right?" Flame princess and Finn nodded in unison, before locking eyes and then turning away once they released what just happened. "What about you, Doc?"

"It's terrible! I don't think I'll ever be the same again…"

"Whoa, Doc, what's wrong? Have you…?"

"Just look at it!" He stood up and gestured to his suit. "It's got dust all over it and it'll never come out in the wash. Plus it was my favourite jacket as well. Wait, I suppose you meant if my being was ok well then in which case I'm completely 100% fi…"

"Ok, ok…jeez I didn't want a monologue. What about you girls?" Bubblegum and Marceline didn't answer or even acknowledge Jake's question. They continued to stare daggers at each other from across the room, much to everyone else's discomfort. It was Princess Bubblegum who struck first.

"See if we'd listened to you we'd be dead!" Bubblegum yelled to the vampire queen.

"When I'm around you I wish I was!" She yelled back. Bubblegum froze and stared, ignoring everything and everyone else around her. "Wait I didn't mean tha…"

"Save it!" Bubblegum snapped, turning her head towards the wall and away from the others so they couldn't see her tears.

"Princess are you…"

"I'm fine, Finn…I just need some alone time, that's all." Silence followed as Marceline too pressed herself against the wall and turned away. Finally Finn spoke up.

"So what's the plan, Doc? Don't mean to push you but these kind of situations you usually have a plan for. Doc?" The Doctor took out his sonic screwdriver and examined it.

"Hmm? Sorry…really I am…I've got nothing. No plan, no backup no nothing."

"Come one, man, surely you can…"

"In no particular order we need to get out of this storage room we're currently trapped in, move several hundred tons of rubble from the pathway, get back to the TARDIS which the cybermen are now standing in the way of, figure out a plan of how to either destroy the cybermen here on this world or get them back through the rift into my universe, save all of your lives and fix Bonnibel and Marceline's relationship. It's a tough sell, even by my standards."

"Yeah that does sound pretty hard…wait what was that last thing you said?" Jake asked.

"Take the cybermen back to my dimension."

"No after that."

"Doesn't matter but what does matter is that we're still alive."

"Yeah," Finn said. "And although we can't get out I'm willing to bet that the cybermen can't get in either, right?"

"Well you're half right," the Doctor half smiled.

"What?"

"We've got about 10 minutes before the cybermen blast their way through the rock and reach us.

"But won't the roof just start to collapse again?" Flame princess asked.

"Most likely but the cybermen are made out of a Cyberian steel alloy. Falling rocks won't stop them. Plus they'll already have weighed up the odds of us escaping versus the roof collapsing on top of them and calculated that…"

"Never mind what they're going to do, what are we going to do?" Flame princess cut him off.

"I told you…sorry but I don't have anything." He rubbed the bridge of his nose. "Even with the TARDIS it'd be a long shot and we don't even have that. Half a mile of rock and nearly 3 million cybermen stand between us and the slimmest chance imaginable." He pressed his back against the wall, dirtying his tweed suit all over again. "I'm sorry…I dragged you all into this and now it's my fault. 3 million cybermen are going to spread out across your world, your universe and it's my fault."

"Don't say that!" Finn said, standing up. "As long as we're alive we still have a chance, you said it yourself. There must be some other way."

"Can't you melt your way out FP?" Jake enquired.

"I'm afraid the whole thing would just collapse again if I tried to…and I'm still not strong enough to do it anyway." Finn noticed how pale her flames were for the first time since they'd had entered the room. The cybermen's energy drain truly had left its mark.

"Well I guess you can use this." The Doctor reached into his pocket and brought out a spoon which he then threw to Finn, who was forced to tear himself away from Flame princess.

"What can I do with this that'll help?"

"Start digging…sorry but it's the best I've got." Finn shook his head in annoyance and dug the spoon into the rock where it promptly bent and cracked. Yelling in frustration he threw the silvery object back against the solid structure and started to kick at the wall with all his might. Bubblegum sprang up at this and ran over to him.

"Finn stop, please. You're just hurting yourself!"

"No I've got to help somehow. People need me to save them!"

"Finn, it's not helping anybody! In fact you're just…"

"Shh!" Marceline whispered to Bubblegum.

"Did you just 'shh' me?! That's it, Marceline, I'm done with…"

"Shh! Listen." The vampire queen lifted her head but didn't take it from the wall where her ear was pressed against the stone. "Can you hear that?" The group stopped and listened, pressing their own ears against the wall." It was very faint but was getting louder by the second. It was a grinding sound, like something was…

"Tunnelling!" The Doctor jumped back and sonic-ed the wall. "The cybermen have recovered and in about 5 minutes the party's going to arrive. If anybody's got any brilliant idea's I'm all ears, in fact I'll take you to a planet where everyone's all ears." The room remained silent except for the ever growing sound of the burrowing.

"No? Well it's been an honour, really it has." The Doctor went around the room in a clockwise fashion and shook everybody's hands, much to their dismay. "We had a good run though, didn't we? The very best of this planet, that's what you are and it's been my honour, my privilege to know each and every one of you personally…"

"…Doctor…"

"And further more…which one of you said that?" The group looked at each other for a few seconds before shaking their heads at him. "Well own up 'cos I'm getting all emotional here and I don't like being interrupted when I'm getting…"

"…Doctor…"

He stopped and looked very hard at each of the faces before him. Reactions ranged from surprise to amazement but one thing was clear; none of them had said it.

"…Doctor…help me, Doctor…"

The group all turned slowly to the source of the voice. It was coming from a small rock at the side of the room, or rather what it was crushing. The Doctor glanced at the group, then at the rock, then at the group and back to the rock again. Cautiously, he crouched down and picked up the rock. He was so surprised at what he found that he nearly dropped it again. Under the rock was the battered, broken body of BMO.

"BMO how did you…?"

"Not now, Jake…we've haven't got much time." His usually cyan coat was blackened with dust and most of his front screen was missing as well as one of his arms, but that didn't stop the little robot from pouring his soul out to them. "I'm so sorry Finn and Jake. They came to me in the nights. Whispered things, did things to me that I want to apologize for."

"BMO it isn't your fault," Bubblegum said. "They corrupted your memory core and forced you to do things that you would never do if you were healthy.

"Oh princess, beautiful princess of bubblegum…it's time to face facts. I'm a robot and I can't be healthy or unhealthy. It's time to stop pretending to be more than a robot. Time to let Football go."

"BMO you can't die…you just can't, not like this." Jake held back his tears. BMO smiled weakly.

"Dying is for the living…and I'm not living and I never was but I understand. I ruined your plan to kill the cybermen but there is one more option. Doctor you know this."

"But you'll die. I could never do that to you," he said, half whispering.

"What does he mean, Doctor?" Marceline said, also holding back her tears.

"Within my data banks is the record of the code needed to destroy the cybermen's emotional relay. Although I destroyed the original transmitter you can still use my body as a replacement." Bubblegum went wide eyed, tears of her own threatening to escape.

"But the power surge will destroy you. Even transmitting that signal for a second will burn up your circuits in an instant. We can't let you do that." BMO sighed, dropping his remaining arm limply down to the side.

"There is no other way, princess. I messed up bad and now I must pay the price for what I have done…forgive me."

"No that was the cybermen that did that. You were just unlucky…" Finn began.

"Finn, please…you haven't got much time before they arrive. Listen." They did and could now here the voices of the cybermen drifting through the rock.

"THE REBELS HAVE BEEN LOCATED."

"RAISE CONFRONTATIONAL DEFENCES TO MAXIMUM."

"ALL WEAPONS SET TO MAXIMUM. THERE WILL BE NO HOSTAGES, ONLY CYBERMEN.

"DELETE."

The Doctor looked down at BMO one last time.

"Are you sure you want me to do this?"

"Yes, Doctor, quite sure. It's what I deserve."

"No. This was my fault and you're paying for it with your life…there is no other way but that doesn't mean we won't remember you. Remember your sacrifice 'till the end of days. People will forever speak of you, BMO. BMO, the hero." BMO closed his eyes for the final time and smiled, content to know that he had finally redeemed himself in the eyes of those he'd wronged.

"Rest well, buddy." Finn and Jake hugged with Bubblegum resting her hand on their shoulders. Flame princess and Marceline looked solemnly on to the Doctor who was busily connecting his sonic screwdriver up to BMO's now empty shell. His body started to glow softly and the sonic gave a conformation that it was primed and ready to use.

"Now all we need are the cybermen." The wall behind them exploded causing everyone to dive for cover. The black-faced cyber-leader, flanked by the rest of the cybermen emerged from the tunnel.

"LIFEFORMS DETECTED. THEY WILL BE…"

"Oh give it a rest!" The Dust cleared to reveal the Doctor was still standing, holding BMO and the sonic screwdriver. "Look at what you've done. All the lives you've taken. You are so, so small, compared to them," he spat. "And now you've forced my hand yet again into becoming that of a murderer. I used to have so much mercy…but guess what, guys?"

"DELE…"

"Night, night." He pressed down hard on the sonic screwdriver, it's usually green light now engulfed in white. The cybermen didn't even have time to register what had happened as the wave rippled through their bodies and through the tunnel, overwhelming their brain-circuit interfaces and rupturing the emotional inhibitor unit that was present in all of them. And without the suppression of their feelings through the relay they began to feel. Feel everything. Feel what had been done to them and what they had done. The cold. The dark. The pain. And it was killing them.

"WHHYYY?!" They held their heads in their hands, some falling to their knees.

"ARRGGGHHH! WHY SO COLD! SO COLD! YEAANRRGH!" Their heads began to rupture and crack from the feedback they were experiencing, some even going as far as exploding completely.

"WHAAATT HAVE YOU DOONE TO USSS?! SO DARK. SO COLD…IT HURTS..." A cataclysmic explosion tore through the tunnel as the cybermen finally felt what it was like to be human again. Then silence returned to the room.

Princess Bubblegum opened her eyes, realising she was on the floor, covered in rubble. Looking upwards and struggling to prop herself up, her eyes filled with dust. Partially blinded, she could just make out the shadowy figures in front of her.

The shadows were screaming in pain, clutching their heads and dropping like flies. They fell down, one by one to the floor and didn't move before being engulfed in fire. Silence. Now only one of the figures was standing. Standing above the fallen…above everybody else as well. The man had no name, defined only by his actions. Forced into genocide when there was no other option and haunted by the screams of those who'd died at his hand. And he was the Doctor. Blinking away the dust, she could see him walk over to her, standing tall.

"Take my hand." She looked at his outstretched hand and back at the shadows which she could now identify as the bodies of the cybermen. She took his hand and allowed its warmth to flow through her once more.

"Thank you, Doctor," Bubblegum said, allowing herself to be pulled up by his arm. "You saved not only us but the whole of Ooo, if not our universe."

"But at what cost?" He stated glumly, helping up Finn. "I killed an innocent being."

"No!" She shouted, making him jump. "The cybermen killed BMO, long before any of us could have known. You can't blame yourself for that. He died believing in what was right and not what the cybermen wanted. You can't beat yourself up for his death; it wasn't your fault.

"…Yeah I guess," he said cheerily, but it was rather artificial in delivery and didn't really hide his despondency in any way.

"No really, Doc, you did it," Jake added as he too was helped up. "I know you think this was all your fault but without you none of us would even be here. None of Ooo would be here."

"Yeah, Jake's right. Thanks to you the whole entire universe is safe. We owe you our lives." Finn said, joining Marceline and the others who had gotten up.

"You owe me nothing, in fact I was never here." He smiled slightly, adjusting what remained of his bow tie.

"Wha…?"

"News of this day will spread across the kingdoms of this land and the events will become known to the world. How a force from beyond the stars was defeated by the heroes of Ooo." He looked around at the faces. "I'm no hero and I don't deserve to be remembered as one."

"But it was your knowledge and technology that helped us in the first place!" Princess Bubblegum couldn't believe what she was hearing, and neither could anyone else for that matter.

"And who was it who was brave enough to infiltrate the crash and recover the code despite knowing how dangerous it was? I only helped you in the quest for peace; it was you, all of you brilliant, brilliant people who did the real work. Never forget that."

"But Doctor…"

"Enough about me…you're safe and that's what matters. Now come on…" his genuinely cheerful demeanour returned once more. "Come on let's get you out of this place and back to reality. Back home."

"NGHHH…NO!" The group spun around to face the source of the voice. The cyber-leader was crawling towards them, its legs having been blown off along with half of its face. Its wiring was now exposed and crackled dangerously with electricity as it dragged itself towards them.

"YOOOUUU…WILL…BEEEE…" it aimed its arm cannon towards them.

"Get behind me!" The Doctor yelled.

"…DELETED!" The cyber-leader exploded at last, but not before it could use its remaining power cells to fire a single blast of energy toward them. The group dived to the ground…but the last of the cybermen hadn't been aiming for them.

Flame princess lay on the floor, overlooked by the others and still too weak to prop herself up from the earlier explosion. Barely conscious enough to move her body, she saw the blast racing towards her and closed her eyes, resigning herself to death.

But death never came for her, as Finn was quicker.

Just when you thought all was well! Hands up if you saw that coming! Well since I can't see them I guess reviewing is the only way I'll know.