A mysterious warrior from another realm who adopted the name of the [[marth (fire emblem)|hero king of old]]. He wields the same blade as Chrom, the Falchion, yet there should only be one Falchion in existence...

[spoiler]This is actually [[lucina (fire emblem)|Lucina]], [[chrom (fire emblem)|Chrom's]] future daughter, who traveled through time to the past in order to change the future for the better.[/spoiler]