- “Come on, Hecaton!”
- —Oerba Dia Vanille, Final Fantasy XIII
The writing on Hecatoncheir and his summon symbol reads:
- By the grace of Etro, arise great and mighty giant. Come forth, thee who shoulders the sky.
- A name in blood, a pact of strength. Hecatoncheir shall rise, his bond eternal and unyielding.
- Impure hands purge arms that fortify weakness.
Fang becomes suspicious that Vanille is hiding something from her, and decides to confront Vanille about their past. In order to get the truth out of her, Fang decides to lie and says that she finally remembers the events surrounding their original Focus. She reveals that she was the one who became Ragnarok and scarred Cocoon many centuries ago.
Although Vanille knows this is the truth, she frantically tries to deny it. As if to reprimand her for lying, Hecatoncheir is summoned and confronts the duo. Fang interprets this as a sign of truth, and Vanille finally admits what she suspected - Fang was indeed the one who transformed into Ragnarok in the War of Transgression. After the battle Vanille breaks down in tears, saying that she did not want Fang to bear the terrible guilt of the beast's bloody rampage, and Fang forgives her.
- Main article: Hecatoncheir (Final Fantasy XIII Boss)
Vanille and Fang first face Hecatoncheir as a boss in Mah'habara Subterra, as a test to prove Vanille's strength to him. Hecatoncheir is the last Eidolon fought in the game.
Hecatoncheir is Earth-elemental and is the only Eidolon that possesses the Quake ability. He is also the only Eidolon that does not have Curaga, meaning Vanille must heal for herself. Vanille's Gestalt Gauge increases by driving up enemy chain gauges, inflicting and removing status ailments and restoring HP. In Gestalt Mode, Hecatoncheir transforms into a Magitek Armor, quadrupedal mech with four machine gun turrets that Vanille can ride.
Hecatoncheir's gameplay concept is Shooting Blaster, and its Gestalt Mode attacks are ranged and places a strong emphasis on the enemies' positions in the battle. Hecatoncheir ignores physical and magical defense and, despite not having a name for the ability such as Penetration used by Odin, Shiva, and Brynhildr, possesses an attribute which similarly reduces all resistance and immunity to elements to no resistance.
|Pummel||1||Inflicts multiple physical damage on opponents within a small radius.|
|Aerial Tackle||1||Inflicts physical damage on one opponent.|
|Hurricane Kick||1||Inflicts physical damage on opponents within a small radius.|
|Force Projection||1||Inflicts physical damage on one opponent from long range.|
|Quake||4||Inflicts earth magic damage on opponents within a small radius.|
|Arise||Auto||Revive ally from KO with full HP. Instantly dismisses Eidolon.|
|Counter||Auto||Sometimes counterattacks opponents after evading their attacks.|
|Looming Wrath||Auto||Attack any opponent that draws near.|
Hecatoncheir in his Gestalt Mode render appears in Final Fantasy Trading Card Game. It has an earth-elemental card.
- Main article: Hecatoncheir#Etymology
- Despite the similarities, Hecatoncheir's Gestalt Mode is not inspired by the Magitek Armor from Final Fantasy VI, but ended up looking like it. A question from Brain Blast in Final Fantasy XIII-2, however, indicates that the reference is intentional, the correct answer being that Magitek Armor is the "vehicle" that Hecatoncheir transforms into in Gestalt Mode.
- Vanille's pose on top of Hecatoncheir's Gestalt resembles Rikku and her Machina Maw dressphere from Final Fantasy X-2.
- Vanille almost always calls him Hecaton. However, she does rarely say Hecatoncheir, pronouncing it "Hec-a-ton-care".
- Due to the serious nature of the battle, Vanille uses alternative lines related to Hecaton during the final boss battle in the game (for example, Vanille summons him by calling out his full name, in addition to using an alternative set of attack lines during the final battle).
- Ragnarok's complete form resembles a fusion of Bahamut and Hecatoncheir, Fang and Vanille's respective Eidolons.