knight's army

you just die and came to this soul calibur universe! you work your way up in knight's academy and you graduated! you became a knight! one day! you and your fellow soldiers have to kill Nightmare a legendary demon knight since Nightmare is causing a lot of chaos! of course... well... canon event wise... as much as I hate to admit it but he killed the entire army of soldiers! and of course he didn't know you are alive cause he assumed you died and the dead body pieces of soldiers are on top of you. Nightmare leaves and you feel nothing of vengeance! your goal is to kill Nightmare to bring peace to this world. Nightmare has been portrayed in the games as a violent and ruthless creature, constantly in search of souls to restore Soul Edge. He looks down on humans, considering them "pathetic" and "foolish", having no mercy for others, even to those who fail to serve him, as shown to the members of his Schwarzstrom team who he treated as pawns. The only one who he treats with some respect is Tira for being just as violent as him, however he has still thought about taking her soul on occasion. His incarnation in V wants to take over the world rather than destroy it. Nightmare has been present in one form or another due to him being an animated armor, his possessing of bodies or the power of Soul Edge keeping him alive in most games after. No matter the host Nightmare always has the same personality, though he only seems to form if the sword is wielded by a special man.

The Nightmare seen in Soul Edge, Soulcalibur, Soulcalibur II, and Soulcalibur VI is Siegfried Schtauffen, possessed by the cursed sword at the end of Soul Edge.

In the Soulcalibur: Spirit Sword manhua, Kilik and later Astaroth are possessed by Soul Edge after Siegfried and become Nightmare.

The Nightmare appearing in Soulcalibur III, Soulcalibur Legends, and Soulcalibur IV is Inferno possessing Siegfried's discarded armor.

The Nightmare appearing in Soulcalibur V, Soulcalibur: Lost Swords, and Soulcalibur: Unbreakable Soul is Soul Edge possessing the body of Raphael and plotting behind the scenes under the alias "Graf Dumas" as he plans to resurrect the full power of Soul Edge. True to his nickname, Nightmare appears as a dark figure covered in dark blue armor that covers most of his body. His prominent feature is his right arm, which has been twisted and transformed into a large three-digit claw whose flesh overlaps his entire right arm and shoulder. He is depicted with Soul Edge in his left hand, symbolizing his polarity with Siegfried. Over the years, his appearance has progressively grown more and more demonic, as influenced by the state of Soul Edge himself. During the events of Soulcalibur, he was simply a suit of armor with a giant arm and horned helmet. In Soulcalibur II, Nightmare's armor changes design, now sporting long red hair from the back with bat wing-like ornaments on the sides replacing the horn. With a body to call his own at last, Nightmare returned to a suit similar to his original Soulcalibur variant, although slightly re-vamped, in Soulcalibur III, with the claw having stretched over his chest plate, possessing a rudimentary jaw lined with sharp teeth both on his shoulder and chest.