AN: This is not what I usually write at all. This is based off the prompt I received for the Cybertronian's group (on DeviantArt) 2013 Secret Santa Exchange. Following their prompt, I wrote an oneshot for the Transformers Prime universe.

Prompt: For Xobit – "Either a story or drawing featuring Vampire Megatron and vampire Optimus, slash-y or fight-y as the artist/author wishes, preferably TFA or TFP based."

Disclaimer: I do not own Transformers Prime.

Sanguine

By ObsydianDreamer

The hunger was overpowering.

He released an involuntary snarl, shaking his head and intaking air to try and clear his mind. He knew that if he did not feed soon, he'd fall into a crazed bloodlust; a state he preferred to release only on the battlefield, against enemy soldiers.

Time was of the essence. Dawn was perhaps only a dozen breems away, and he'd seen what sunlight did to those infected with the vampirism virus. Bodies sent to the labs for investigation; curled and frozen in agony where their bodies had reacted so violently with the sunlight that they had simply turned to rust.

Stalking silently through the shadowy back alleys of Kaon, he eventually spotted his prey. A small mech, perhaps half his size, walked with his back turned. It was an easy target.

He began to follow the mech, his pedes treading lightly, but quickly, on the ground to avoid warning the victim. He could smell the mech's fear, and he moved faster. When he got close enough, he lunged, grabbing the mech and tackling him effortlessly to the ground.

The mech didn't have enough time to scream, let alone fight back. Within astro-seconds, he had sunk his fangs into the victim, tearing at the sensitive cables on the side of the neck, causing precious energon to flow out. The mech tried to fight back, but it was for nought; he soon went limp as his lifeblood was drained out. Within a klik, he had been drained dry.

Having quenched his thirst, his sense began to return to him.

Megatron looked around at the dark alley, almost confusedly. Where was he? Hadn't he been in the war room just before? He looked down at the dead mech, and tasted the fresh energon in his mouth, understanding.

His hunger temporarily sated, Megatron leaned back against a wall, pushing the lifeless corpse to the side. Curious, he checked the insignia of the mech, wondering just who he had killed. It was a Decepticon soldier, one of low rank. Megatron cursed; they would need every capable soldier they could find if they were to win the war, and since they'd released the virus, the number of sane and stable individuals had dropped.

The virus had been designed, created and released by their Biological Warfare Program. It was supposed to be the successor to the Cybonic Plague; a virus not made to kill though, but to mutate. It staled the energon within its victims, requiring the infected to consume the lifeblood of other, non-infected cybertronians. If they did not feed, they became frenzied, attacking anything insight.

Megatron glanced at the dead soldier next to him. Despite feeding as often as necessary, his lapses in control were becoming more and more frequent. And if he was losing control, he could only wonder how the other, lesser victims were coping.

On the upside though, the virus gave its infected very little weaknesses, apart from the near constant need to consume live energon. Sharp objects, or indeed anything they made them bleed out did extra damage, and sunlight, even when filtered, rusted them to death within seconds. However, as an unintended bonus of the virus' engineering, after an infected individual fed, they would become effectively super-charged; making them stronger, and faster.

Under most circumstances, Megatron would not have allowed himself to become infected with a created virus, or at least have designed a cure first, but this was a special case. This time, he ensured that he had been the first to be infected by it. The virus spread by bite, providing that the feed didn't kill the victim. Afterwards, the new vampire was only slightly above a mind slave to the one who had turned them. By ensuring he was the first, not only was he the strongest, but it also gave him control over all of the mechs who had been mutated. Some control, anyway. As it filtered down and more and more mechs turned, his control over them lessened. They became more unstable though, losing the ability to effectively control themselves.

Sighing in contentment, Megatron shut off his optics. How much time passed as he rested, he did not know; he only stirred when he heard soft pede-falls come towards him. From his place against the wall, Megatron saw a familiar shadow approach.

"Consuming your own soldiers now?" Optimus Prime commented, disgust evident in his voice. His armour seemed duller in colour than usual; something about the Prime was off.

"Merely collateral damage," Megatron replied, shoving the body away and standing up. When the moment came, it would be all too easy to kill the Prime. Having just fed, he was way stronger than the Prime could ever be. "Why are you here, Prime?"

"A cure. There must be one," Optimus replied. As he spoke, Megatron noticed that the Prime had long fangs, not unlike his own. Realisation dawned; the fangs, the discolouration, it all meant one thing.

"You too, Prime?" Megatron said, as he began to laugh. "I knew it was far reaching, but I did not imagine it would reach top Autobot command."

"Answer my question," Optimus Prime demanded, becoming more frustrated. "Is there a cure?"

"No," Megatron replied. It wasn't a full lie; the virus had been released before a full medical cure could be created. There were some ideas of how the virus could be stopped though. Shockwave had the theory that since Megatron was the first infected, if he somehow died, the others would be released from the mind control and thus most likely the disease.

But he was not about to tell the Prime that. Flexing his claws, he moved towards the Prime. This was going to end in a fight, and the fight was going to end with the Prime dying gloriously at his hands. But time could not be wasted; the sun had started to rise.

"Was it worth it?" Optimus asked, drawing his blade. Megatron did the same, and the two mechs began to circle each other.

"Well, the Decepticons are winning, aren't they?" Megatron replied, before charging forward, swinging the blade.

Optimus narrowly sidestepped, before meeting the blade with his own. The power behind the attack almost sent him back.

The virus had made him far faster and stronger than he was before, but it had done the same to the Prime. They were too evenly matched. The fight continued, with neither one giving ground as they fought in the little shadow that remained. Every attack with a blade and every punch was met equally, and neither made a mistake.

In the end, a small error ended the battle. Optimus overshot the swing of his blade, and Megatron took his chance, piercing the Prime's shoulder. But before Megatron could finish him off, Optimus used the last of his strength to plunge his blade into the Decepticon leader's chest, stabbing him just centimetres from his spark.

Instantly, he felt his life and energy leave him as his energon bled out. Prime wasn't doing much better; despite getting a lesser injury, he was still struggling to stand. Their energon mixed together as they both bled out, making blue pools at their pedes.

He could not die like this. He could not. He looked at the Prime in fury, and tried again to fight back. It was no use; there was so little energy left. His vision began to blur around the edges, and his pedes failed from under him, causing him to lean on the Prime, much to his own disgust. Optimus, meanwhile, seemed thoughtful, even as battle damaged as he was. He looked serenely at the sunlight, and began to drag the two of them toward it.

Megatron knew instantly what the Prime was planning to do.

"You'll kill us both!" Megatron hissed, continuing in vain to struggle.

"A sacrifice I will make," Optimus replied calmly, before throwing them both into the sunlight.