alter_servant

Theoretical fan-designed dark persona version of a character who has been (theoretically) corrupted by the mud of the Fuyuki Holy Grail from Fate/Stay Night, similar to canon examples like Dark Sakura or Saber Alter. Fan examples of "alters" include Archer Alter (fate), Lancer Alter (later made cu_chulainn_alter_(fate) in Fate/Grand Order), or the "Sabatsugu" version of Emiya Kiritsugu (not to be confused with Emiya Kiritsugu (Assassin)).