On a planet far from home, a solitary siren sped through the wine-dark sea toward her quarry, swifter and more deadly than a long-extinct shark. Her target, a Human ship, lay becalmed in the waves. Almost as if it expected and awaited its fate.

Halcyon the siren paid no thought to the ship's passengers or crew as she hauled herself up the Poseidon's anchor chain to the deck. She listened for one voice and one voice alone – a prisoner the Humans had taken. A civilian they had no right to take.

As she stalked the deck, she lifted her voice in song. Humans heard and fell into slumber. Those who already slept sank deeper still. Deadly music echoed along the passages as she passed, until she heard a pained gasp, followed by, "Halcyon, dearest, you should not be here!"

Halcyon wrenched open the hatch that was all that lay between her and her husband. Except that the man she beheld no longer looked like her husband, for all that he spoke with Ceyx' voice. The bloodied piece of meat strapped to a table before her didn't look like a man at all, let alone a living one.

"What have they done to you?" she whispered, reaching out to touch the man she loved.

The homunculus coughed, bringing up more blood, which he spat on the floor. "Tortured me for information, dearest. They think me one of them, and a traitor. My research – " He coughed again, more thickly this time. "My research is what they wanted. Human and Titan genetics. They are the same. The same, dearest. We can breed with them and they with us. Worse, if they work out how to bestow Titan powers on their own, they will annihilate us. That is why they tortured me. I refused to experiment on them. To work for them. I will not be a part of – " A deep, hacking cough seized him, leaving him gasping for breath that he was unable to draw from the air.

An eternity passed in a moment, as Halcyon was forced to watch her husband suffocate to death, like a fish out of water.

Her blood boiled within her veins. Titans were violent, yes, but none would dare harm one of the Mer, let alone attempt to torture one. Not like this. Not knowing what one siren could do to thousands of them.

Halcyon scanned the room, her fingers itching to show them what she thought of such despicable tactics. Her gaze lighted on a slumbering Human, almost hidden under a bench. Sleep was a luxury he would never know again.

"Wake," she commanded him, first in her language, then his own when she got no response. The ignorant Human didn't speak Mer, so she would speak in English, and in pain. Both languages he would understand before he died.

The man blinked, patting down his lab coat that looked so much like the one Ceyx once wore to work. No more.

Halcyon ripped the plastic name tag from the man's chest. "Get up, Doctor Claudius Tasker. Did you do this?" She pointed at Ceyx' corpse.

"The traitor wouldn't talk," Tasker grumbled.

"So you tortured him?" Halcyon demanded. "A doctor. A healer. You caused harm that killed him?"

"I had to. The traitor wouldn't cooperate," Tasker said.

His last words. Halcyon screamed, a wordless sound that didn't need words.

Tasker clapped his hands over his ears, but it was already too late. Blood streamed from his eyes and nose as Halcyon hit the precise frequency that made every blood vessel in his head burst. The man dropped to the floor, as dead as Ceyx.

But one life was not enough. Ceyx would not want his research to become widely known, especially among Humans. That meant destroying all knowledge of it on this ship. In data banks. On paper. And inside Human heads.

A bereaved siren's grief knows no bounds, and a siren seeking vengeance for murder would make her fury known. She was the storm no Human could escape.

Halcyon raised her voice again, louder than before, as she marched with gruesome purpose to the bridge. There, she found Humans sprawled all over the floor and the consoles, but she didn't need to wake them to find what she wanted. She had spent six years studying Human technology, as her husband sequenced their genetic code.

She turned on all the pumps, flooding the ballast tanks with seawater until it sloshed into the cargo hold and overflowed into the lower decks, too. She would send Ceyx to a fitting grave in the ocean depths, and all aboard the Poseidon would rest with him.

When she dived from the deck into the waves, the ship sat so low in the water she could reach over the gunwale with her hand. Not for long. The Poseidon sank beneath the surface, leaving only a single floating lifeboat to mark its existence. A lifeboat, where there was nothing but death.

And Halcyon, who would exact a siren's vengeance from all the Humans who had summoned the storm by daring to steal her husband from her, even as she cried an ocean of tears for his loss.

Neutrality was a luxury for other sirens who had not lost a lover to the barbarous aliens. Now, for the first time in living memory, a siren went to war.