Written for Gehayi in the 2011 Ides of April exchange. Title from a line in Cymbeline.

Prompt: "Crossover. Iachimo and Iago are the same person, which is why his plot to smear two innocent wives of army leaders is so similar. How is this man, whatever his true name is, managing to travel through time? Why is he so intent on bringing down Posthumus and Othello? Is it purely jealousy, or are there other factors? Is he successful?"

Invidia sat on the roof of a temple in Sicily and let the breeze ruffle his wings. He went by many names over the centuries; Iago and Iachimo and John, and later 'demon' and Mephistopheles, but Invidia was one of his older names, and we may as well call him that. Invidia was pleased with himself. As was his habit at such times, he sang a little song to himself, though if any mortals were nearby it would seem to be only the droning of bees in the clover.

There was a fluttering like the wings of doves, and Fides landed on the roof beside him, her form like an old woman's. "This isn't over yet," she said.

"The prince is dead, the queen is dead, and the princess will be dead in a little while."

"Hermione isn't dead."

Invidia flapped his wings pettishly. "You people cheat," he said. "I know she was dead." Fides made no reply. "Anyway, it doesn't matter. She'll never forgive Leontes."

"That's not certain."

Invidia smirked. "I have a near-total victory here. Do you possibly think you can salvage this?"

"Then I'll make a bet with you," Fides said. "If I can reconcile Leontes and Hermione, you have to stay out of Sicily for a thousand years."

"And if you can't?"

Fides hesitated. "Then I have to stay out of Sicily for a thousand years," she said reluctantly. "And you know I will keep my word."

"Done," Invidia said immediately.

It took sixteen years, and Invidia had almost forgotten about it, when Fides came back to him. "Look," she said triumphantly.

Invidia looked, and scowled. "Fine," he said. "But I'll spend the time thinking of something really good for Sicily." In the meantime, he flew off to Rome. Jealousy for power was also part of his domain, and there was always something to be done in Rome.

Much later, Fides hovered over a pile of bodies in the emperor's palace and gave him an appalled look. "This is your fault," she said.

"No, this is completely your fault," Invidia retorted. "Roman virtue at its finest. I had nothing to do with it. If Andronicus hadn't been obsessed with his daughter's purity instead of her happiness – And human sacrifice? Cannibalism? Eww. Who does things like that? To be honest, I think you got carried away with the Romans," he added helpfully.

Fides was silent for a long moment. "I am going to have a long talk with Revenge," she said, and flew off.

Time passed, but Invidia still found Rome fertile ground for his plots. Calling himself Iachimo, he took his opportunities as they arose. It was childishly easy to draw Posthumus into a quarrel by insulting his lady-love. Thinking bitterly of Fides and her bet, Invidia suggested a wager. Whenever Posthumus began to think better of it, or his host Philario tried to smooth over the quarrel, Invidia added more taunts, and of course Posthumus was his. They all gave in to jealousy, eventually. Bound by his own word, Posthumus wrote a letter praising Iachimo and commending him to his wife as 'one of the noblest note'.

"It is you, not I, who betray Imogen," Invidia said mockingly, lying at ease in his cabin on the ship to Britain. "For you commend to her one you know well to be a villain, who means ill to you and worse to her. Oh the world, the world! It is scarce worth tempting men to evil, when they leap into it so readily of themselves."

Arrived in Britain, he stirred up jealousy in Imogen. Invidia would have put an eternal rift between her and her lord, but he became carried away with his own success and tried to tempt her into lust. Lust was outside his domain, Invidia thought. No wonder she refused him. But it was a simple matter to talk himself into her good graces again, until she even pleaded with him to stay longer.

Though Imogen indignantly defended her husband's loyalty, she could not drive every doubt from her mind. Invidia lurked in her thoughts, and it was Imogen herself who carried him into her bedchamber.

Back in Rome once again, Invidia regaled Posthumus with false evidence of Imogen's infidelity and left him planning his wife's murder. In retrospect, Invidia should have supervised him more closely, to make sure the man either chose a reliable agent or did the deed himself. After all, one doesn't find spare murderers lurking behind every bush. But it was so entertaining to tempt Augustus Caesar into demanding tribute from every part of the civilized (and uncivilized) world. (Britain was definitely the latter.)

Fides averted tragedy, though only barely, by use of the faithful servant Pisanio and a good deal of luck.

"You weren't expecting Belarius and the King's sons either," Invidia said, once the mortals stopped paying attention to him. "Admit it! You completely lost track of them."

"Belarius and Euriphile were strangely faithful and unfaithful," Fides said meditatively. "But in the end, their better nature prevailed."

"Their better nature, nothing!" Invidia raged. "Imogen should have been dead three times over."

"She was never truly in danger," Fides said serenely. "No one would ever have killed a being as pure and innocent as Imogen."

Invidia smiled thinly. "You think so?"

Venice was a delightful place for a being of Invidia's talents. In Venice, he found a woman who was fool enough to marry him. Because it amused him, he tormented her by pretending to be jealous. Then the wars came, and he was swept along to Cyprus. He had learned from his mistake with Posthumus; humans were slippery creatures, and you couldn't just trust one to go off and kill his wife even if he swore he would do it. Iago, as he called himself, made certain to stay close by Othello's side, urging him on until it was far too late.

Cyprus was his clear and unqualified victory. It was a pity he didn't manage to kill Cassio and make a clean sweep of it, but unless the man changed his philandering habits, Invidia rather thought he might have another chance.

"Are soldiers always this gullible?" Invidia asked rhetorically.

"Indeed, a soldier should be ashamed of being tricked by an enemy," Fides said, quoting a speech in Xenophon, "but with a friend, it seems to me more shameful to deceive than to be deceived."

"Shouldn't a general know how to tell a friend from an enemy?"

And Fides found nothing to say to that at all.

Invidia had been considering for a long time what to do with Sicily. At last, he took the form of a strong young man and called himself John, a bastard brother of the Prince of Arragon. He buzzed and hummed in the ears of every discontented man in Spain and Italy, and stirred up a beautiful civil war. It didn't even matter that he lost. The point was to cause misery and suffering.

And then the chance to slander fair Hero simply fell into his lap. Claudio was another of those sincere, simple-minded soldiers; Don Pedro was little better, in spite of his greater experience with the world's deceits. Invidia gave them only the slightest nudge, and they repudiated Hero and shamed her on her very wedding-day. It was neatly planned, if he did say so himself.

He did not interfere with the plot to match together Beatrice and Benedick, certain that the outcome could only give him sport. When Benedick challenged his dear friend Claudio to fight to the death, Invidia could have laughed aloud.

Everything was going so well, but somehow it slipped away from him. Invidia perched gloomily on the church spire and watched two merry couples leading the dance.

"Foiled again," said Fides.

"Aren't you ashamed to use lumpen clodpoles like those watchmen?"

"They are faithful to their duty."

Invidia did not dignify that with a verbal response. Instead, he gave a loud mocking whistle. He would show her, the next time. And there would be a next time; there always was.