—In-game description from Echoes.
The Fafnir (ファフナー Fafunā), or Fáfnir, is an enemy-only class first introduced in Fire Emblem Echoes: Shadows of Valentia.
Echoes: Shadows of Valentia
Fafnir's description states it is ancient tribe of dragon and units of the class are labeled as members of the Dragon Brethren.
In gameplay, Fafnir acts as a stronger variant of the Necrodragon, using a purple variant of the Necrodragon model. The Fafnir boasts high Defense and Resistance that render it difficult to slay and attacks with Fangs just like the other dragon zombies. It appears rarely in Duma Tower, Fear Mountain Shrine and Duma Temple.
Fafnirs here are the promoted forms of Manaketes, though the only sign of that is the fact Fafnirs outside of Velezark's army (which are completely jet black) have golden wing membranes and spinal ridges, as well as retaining a weakness to dragon-slaying weapons. Fafnirs that are affiliated with Hoshido are called Great Ryujin.
Fáfnirs return in Heroes as a flying variant of the Manakete, albeit with a slightly different spelling of the name. They debuted as a new generic enemy class in Chapter 1 of Book III, utilizing Red, Blue, and Green Breath as a weapon.
In Norse mythology, Fáfnir (Old Norse and Icelandic) or Frænir is a son of the dwarf king Hreidmar and brother of Reginn, Ótr, Lyngheiðr and Lofnheiðr. After being affected by the curse of Andvari's ring and gold, Fafnir became a dragon and was slain by Sigurd/Siegfried.
- Despite the lore describing Fafnir as a Dragon tribe member instead of a monster, in Echoes: Shadows of Valentia, Fafnir is a Terror type enemy (similar to the Necrodragon) instead of a Dragon type (compared to the Dagon and Fire Dragon classes). This is likely a result of the class reusing assets from the Necrodragon class.