marth (fire emblem awakening)
A mysterious warrior from another realm who adopted the name of the hero king of old. He wields the same blade as Chrom, the Falchion, yet there should only be one Falchion in existence...
This is actually Lucina, Chrom's future daughter, who traveled through time to the past in order to change the future for the better.
This tag implicates lucina_(fire_emblem) (learn more).