Kingdom Hearts III: The Heart's Greatest Weapon is a Kingdom Hearts fanfic written by heroes1202. This fic follows the events of Kingdom Hearts II and later, during part 2, Kingdom Hearts: Birth by Sleep and Kingdom Hearts coded. While investigating a mysterious temple on the Destiny Islands, Sora and his friends discover it is in fact a haven for the souls of deceased Keyblade wielders, and that a mysterious new enemy seeks to use their power to access Kingdom Hearts and destroy the worlds. Forced on another adventure, Sora travels the worlds to recruit his most trusted allies and assemble a team to combat the new threat.
The fic is split into two parts, The Heart's Greatest Weapon and Eternal Light. In addition to the typical Disney and Final Fantasy characters, the fic also throws in characters from Tales of Symphonia and its sequel. It also features characters from other Disney and SQUARE ENIX franchises such as Spectrobes and Star Ocean: Til the End of Time.
This fic contains examples of the following tropes:
- Action Girl: Kairi, Xion, Marta, Presea... the list goes on and on.
- Aerith and Bob
- Alternate Continuity: Goes without saying, but still...
- Alien Non-Interference Clause: Subverted. When giving a speech to his team, Sora states that the fact that so many people from different worlds are assembled in one place proves that the worlds can be aware of the presence of others and aims to make their presence known to everyone.
- Animated Armor: The Lingering Sentiment.
- Back from the Dead: In the final battle, the Dark Knight brings back all of Sora's previous foes to battle him and his accumulated forces.
- Big Bad: The Dark Knight, a.k.a. Vanitas.
- Big Bad Duumvirate: Though the Dark Knight is the main antagonist, Xehanort is also a major threat as well. In addition, the gang also has to deal with the Legion of Chaos, a group of Final Fantasy villains.
- Big Damn Heroes
- Big Eater: Stitch.
- Blood from the Mouth: Marluxia coughs up blood as he dies.
- Brainwashed and Crazy: Cerberus, when Lilith gets done with him.
- Continuity Nod: When Seifer and Leon meet in Radiant Garden, they both agree that just seeing the other ticks them off for some reason, a nod to their Final Fantasy VIII counterparts' intense rivalry.
- Crossover / Massive Multiplayer Crossover: In addition to Disney, Final Fantasy, and Kingdom Hearts exclusive characters, the game also features the protagonists of Tales of Symphonia and Spectrobes. It also features Flotsam, one of the villains from Dark Cloud 2 and the main cast of Star Ocean: Til the End of Time.
- Dark Is Not Evil
- Dark World: The Realm of Darkness itself.
- Eldritch Abomination: Darkness is a massive creature who spawned the Heartless and, by extension, the Nobodies, and took over Kingdom Hearts itself.
- 11th-Hour Superpower
- Even Evil Has Standards: Kefka tricks Lock, Shock, and Barrel into planting bombs all over Halloween Town, and they turn on him and cheer Sora on when they discover that said bombs are real.
- Fighting from the Inside: Kairi is briefly possessed by the spirit of the Keyblader Elisa and manages to fight back with Sora's help.
- Mix-and-Match Critters: The Dark Knight has the power to combine all of the different breeds of Heartless and Nobodies to make powerful beings known as Lifeless.