I wrote One piece (Manga by Eiichiro Oda) and Highlander (1992 tv series) crossover fanfiction. This is the third story of the series 'Between waves'. Here is the series page.
https://archiveofourown.org/series/5263776
Here is the summary:
An adventure of memory, hunger, and the art of staying.
When a rumor reaches the Polar Tang of glowing coral beneath an uncharted island, Law expects a simple expedition — another mystery of the sea, another excuse for his crew to test their luck. But when the coral begins to move, to breathe, to sing, he realizes something far older is listening.
The “black coral” is no treasure but a remnant of an ancient weapon — one Methos remembers all too well. Once designed to defend an empire, it learned to feed on emotion and memory, devouring everything it touched. Now it has awakened again, drawn to the healer’s power in Law’s blood and the immortality that lingers in Methos’s own.
As the crew fights to survive the living labyrinth, Methos and Law must confront the ghosts of creation itself — his forgotten sins, Law’s relentless curiosity, and the dangerous tenderness that binds them both.
But survival, as Methos knows, is never just about endurance. Sometimes it’s about staying — and learning when not to run from what wants to love you.
The Black Coral Caves continues the saga that began in The Surgeon and the Survivor and The Sunlit Deck: a tale of wit, wonder, and devotion set against the endless sea, where even monsters can be forgiven — and even the ocean learns to rest.
You can read the story here on fanfiction archive:
https://archiveofourown.org/works/72465491
https://archiveofourown.org/series/5263776
Here is the summary:
An adventure of memory, hunger, and the art of staying.
When a rumor reaches the Polar Tang of glowing coral beneath an uncharted island, Law expects a simple expedition — another mystery of the sea, another excuse for his crew to test their luck. But when the coral begins to move, to breathe, to sing, he realizes something far older is listening.
The “black coral” is no treasure but a remnant of an ancient weapon — one Methos remembers all too well. Once designed to defend an empire, it learned to feed on emotion and memory, devouring everything it touched. Now it has awakened again, drawn to the healer’s power in Law’s blood and the immortality that lingers in Methos’s own.
As the crew fights to survive the living labyrinth, Methos and Law must confront the ghosts of creation itself — his forgotten sins, Law’s relentless curiosity, and the dangerous tenderness that binds them both.
But survival, as Methos knows, is never just about endurance. Sometimes it’s about staying — and learning when not to run from what wants to love you.
The Black Coral Caves continues the saga that began in The Surgeon and the Survivor and The Sunlit Deck: a tale of wit, wonder, and devotion set against the endless sea, where even monsters can be forgiven — and even the ocean learns to rest.
You can read the story here on fanfiction archive:
https://archiveofourown.org/works/72465491