Holding Back the Sea is a Fate/Zero/Percy Jackson and the Olympians crossover. Instead of a dark knight, Kariya instead summons the son of Poseidon, Percy Jackson, as Berserker.
Can be found here: Thread 1
, Thread 2, Thread 3, and Thread 4. A more polished version can be found here. Sadly, the story has not been updated since 2013.
Holding Back the Sea contains examples of:
- Action Pet: Percy can summon Mrs. O'Leary as one of his Noble Phantasms.
- Cutting the Knot: Seeing that his Master Kariya is dying and could meet his end while the Grail War is still taking place, Berserker decides to go to Matou Manor, kills Zouken, floods the worm-infested basement, and abducts Sakura, fulfilling Kariya's wish in less than an hour without the sacrifice of multiple Servants.
- Enemy Mine: Several times, Servants team up to take down a common enemy.
- Lancer and Berserker team up to fight Saber, and they are only prevented from defeating her thanks to the intervention of Rider.
- Giant Wall of Watery Doom: Percy makes one to attack four other Servants at once.
- Heart Is an Awesome Power: As he comes from the modern era, or at least a version of it, Percy is much more aware of things that would be considered common sense that other Servants wouldn't.
- I Am Not Left-Handed: Percy makes it look like Saber has him dead to rights, before breaking out his water abilities and fighting seriously.
- Nigh-Invulnerable: Nothing the other Servants can do can harm Percy in even the slightest.
- Right for the Wrong Reasons: Several people are able to pick up on some of his origins and his abilities, but this causes them to conclude that Percy is Achilles.
- Troll: Percy seems to go out of his way to mess with Gilgamesh whenever he can, always referring to him as "Your Highness" in a sarcastic manner.
