Description from original post (created 2013-07-27 12:37):
Fefnir voiced by Kazuya Nakai, is the leader of the "Army of Ash Flames" of Neo Arcadia. Fefnir's schematics were based on that of X's capabilities of ground combat. He is one of the Four Guardians designed to protect Copy X. He wields two arm cannons, named Sodom and Gommorah. He was faithful to Copy X and oversaw a pupil, Anubis Necromancess III. His original purpose was to clean the land after the Eurasia incident. Fefnir also appears in Mega Man ZX as Biometal F. Vent or Aile can use Biometal F after combining it with Biometal X to become Model FX.
In the first Mega Man Zero, Fefnir launches an assault on the Resistance Base, and tries to defend Copy X, ending up defeated both times. After Copy X is destroyed, he defends Neo Arcadia, and tries to stop Elpizo from infiltrating the Sanctum of Yggdrasil, the location of the original X's dormant body. He became infected by the Baby Elves' power, transforming him into a form that resembles a tank, and only becomes cable of wanting to fight Zero. Though defeated, Fefnir is not destroyed, and later takes part in mission to investigate the wreckage of a crashed spaceship that contains the exiled Reploid, Omega at the beginning of Mega Man Zero 3. He is heavily damaged in the battle and doesn'y not reappear again until the final battle with Omega, only being mentioned, along with Leviathan, once in the game, in which Harpuia remarks to X that "Fefnir and Leviathan are still undergoing repairs". Fefnir, along with Harpuia and Leviathan, died at the end of Mega Man Zero 3 under Omega's explosion.
Fefnir also appears in the Manga adaption of the series. He is no longer a copy of X but a new type of Reploid altogether. He was the first to fight Zero and was defeated. When Zero was brought before Cial(Ciel's evil twin), he rejected the thought, stating that he would be watching Zero. Fefnir's(along with Phantom and Leviathan's) suspicions were correct when Zero took Cial hostage. After they got Cial out of Zero's reach Fefnir and the other Generals merged to form "the ultimate reploid"(Copy X) and was destroyed by Zero.