A/N: This chapter is also rated a definite M, for one pretty graphic sentence down near the end, but the rest of it is also rather dark and creepy and I blame getting one hour of sleep out of the past 36 hours.

Anyway. Enjoy, and I'll go sleep, and maybe write something a bit more cheerful next time...

...but you guys probably saw this coming.

Forbidden Fruit

Every day, Optimus thought that it had been long enough, that the wounds had finally healed, that she could finally move on and end this war decisively, with no more feelings of guilt or regret. Every day, she hoped that she had finally abandoned those last stubborn pangs of sorrow.

And then there would be a battle, another clash sure to leave many casualties; she would see him again, and all her illusions of detachment would shatter. Every time she saw him, she couldn't help but remember how it had been before… how she'd felt about him. How she still felt about him.

She twisted one glowing blade in a now thoroughly dispatched Decepticon soldier – at times it horrified her how easy killing had become, but never during the battle when a distraction could prove fatal – and saw him nearby, mowing through her Autobots with the deadly grace that she couldn't help but guiltily admire even as fury bubbled up within her at his actions.

"Megatron!" she called, her voice raised to nearly a bellow in order to be heard over the sounds of battle. She braced her foot against the dead soldier and tugged her sword out, leveling the blade at her meters-distant foe. "This ends now!"

He paused, the area around him cleared, and shooed Brawl away before turning to face her with a smile that, even here and now, made her insides twist and curl in girlish giddiness.

And then Megatron laughed at her. He threw his head back and indulged whatever sudden surge of merriment had seized him, letting his guard drop completely, and Optimus could do nothing but stand and watch him, seething silently until he wound down.

"Optimus Prime," he answered smoothly, quieter than she had been but still loud enough for her to hear him quite clearly. He shifted a leg back and bowed courteously, mockingly, never taking his piercing crimson eyes from hers. "As charming as ever."

"We can't all be groomed as nobility from birth," she retorted, advancing cautiously. He had lowered his weapons, but she knew that he could have them up again at a moment's notice.

"Yes, please pardon me. I forgot that some of us hail from the vile breeding pit of the docks."

"Insulting my background may be unwise, Megatron," she warned him, controlling her anger and letting it flow instead to her hands, which tightened on her swords.

"Forgive me, my lady." He half-bowed again, his smile slow and sinister. "I'm sorry that all of this fighting has made me lose my manners."

"Save them for Primus's court. You'll need them."

He matched her approach boldly, seemingly careless of her dangerous weapons, and his eyes narrowed slyly. "Going to send me to him so soon, Optimus? Are you sure you have the nerve?"

"Nerve enough to rid this world of the threat you pose to it." Prime was glad that her voice carried more conviction than she actually felt, but Megatron seemed to see right through it. His measured predator's steps brought him within range, but she didn't strike.

"You can't kill me, Optimus," he murmured softly, and as he drew in close enough to reach out and touch, the swords fell from her numb fingers, clattering on the ground where they fell. She looked up at him, helpless and bewildered and lost and frightened, but paralyzed like a bird trapped in a serpent's hypnotic stare. His surprisingly warm fingers touched her pale cheek.

"We don't have to fight," he whispered. She tried to suppress a shiver and failed, drowning in the silky smoothness of his voice, the sweet promise of his touch. "We can live and rule side by side as we are meant to… as we once did. Come with me."

He kissed her, drawing her, unresisting, into his arms; although some part of Optimus told her how wrong this was, the rest of her responded, eagerly even, and she melted into it, surrendering utterly to his hold, his touch.

"Megatron," she sighed in a barely-audible puff of air, like a secret prayer to a dark and forbidden god, before they came together again. She responded to his passion with her own, tasting, savoring, submitting, losing herself in his taste, his scent, his touch…

A faint shout had the effect of a bucket of ice-cold water. Optimus jerked back, heat rising to her face, as she realized that a familiar voice was calling her name, her soldiers searching for her. The hint of a sneer pulled at Megatron's mouth.

"Your loyal tin kettle is looking for you."

Ironhide, Optimus realized, now recognizing his voice. Megatron was already retreating, drawing rapidly away.

"If you should want to end this war, Optimus, remember that I am always willing to accept your surrender," he called back to her, then was gone.

"Optimus!" Ironhide came running up, gentle hands coming up to her arms. "Are you all right?"
"I… yes," she lied. He hadn't seen her weakness, her betrayal. "Just shaken, that's all."

"The Decepticons are falling back to their base, probably to lick their wounds."

"Then we should fall back as well. We've stalled their advance; that was our purpose. There's no sense in wasting lives trying to reach them behind their armature."

Ironhide hesitated. "Are you sure you're all right?"

Optimus might have given a thousand excuses. In the end, she used none, but stepped forward to rest her head on his shoulder. Ironhide's strong arms wrapped around her in a comforting embrace and she hid her face safely in his chest.

It shouldn't be this way. The man she loved was gone… or, rather, he had never existed. It had always been a façade to manipulate her… and how superbly it worked, even now: when Optimus couldn't stop thinking of him, day or night; when she woke with his name on her lips. There had been other touches, other poisonous kisses, and worse; there had been the time that she had contacted him for no other reason than to see him, and he had laughed and laughed and finally had said something in a tone just biting enough that she'd had the strength to pull away; there had been the battle where she'd fallen into his arms and their panted breath had mingled in the privacy of a half-demolished corridor, his fingers questing down and finding her already wet and dripping, slipping inside and working her until she writhed on his hand, moaning and gasping and shuddering as she climaxed hard… or had that been only a dream?

Every day, Optimus thought that this would pass, that this was a mere infatuation or, at worst, a severe and entirely inappropriate physical attraction that would fade away at any time.

Every day, Optimus was forced to admit that this was so much more than sheer physical desire; that she loved him, incurably so; and that if there was even the slightest chance that he might find goodness and light, Megatron was right: she could not kill him.