"Hey're not even hurt...why are you crying?"
— Seth Knighthorn

Seth Knighthorn is a mage and former test subject for the Magical Research Association. After breaking out of the laboratory and killing many researchers, Seth becomes a wanted fugitive and has crossed paths with the Fairy Tail guild on more than one occasion. Seth is the only compatible user of Chaos Magic, an art he is still having trouble controlling.

Seth Knighthorn
Name Seth Knighthorn
Romanji {{{romanji}}}
Race Human
Gender Male
Height N/A
Weight N/A
Eyes Red
Hair Black
Unusual Features Cackling, Twitching, Pale skin
Professional Status
Affiliation None
Previous Affiliation MRA
Occupation None
Previous Occupation Test Subject
Base of Operations Cave in a remote mountain
Personal Status
Marital Status Single
Relatives None
Magic Chaos Magic
Assimilation Magic
Image Gallery


Seth appears as a tall, young adult male with red eyes and black hair. Due to his extensive time confined to an underground facility, his skin is pale. Seth wears a variety of clothes, but is recognized best for wearing a brown vest that covers his chest over a black shirt, and long blue pants. He wears four belts. One around his waist, one around his torso, and two on his left arm. These belts are leftover from the strait jacket he used to wear.

On his waist, Seth has a holster of some sort strapped in. Inside is a broken ring, which he referred to as 'it's the last of the puzzle'.

Personality & Mannerisms

Seth has shown an incredibly random personality. Due to the extensive experiments performed on him by the MRA scientists, Seth's mind is rendered all but insane. His mood can drastically change without warning; he can be cackling joyfully one moment and then suddenly start clutching his head and screaming the next.

In battle, he is incredibly sadistic and enjoys the thought of murder. When he escaped his bonds, Seth began giggling when he realized he was about to kill all of the men who once tormented him. When up against strong opponents, he constantly twitches in excitement and licks his lips when he is about to attack. When in a battle frenzy, Seth seems to lack any compassion and will attack indiscriminately. Thanks to his random personality, however, Seth can also simply ignore opponents and walk away from the battle.

On the other hand, his lack of any education and virtually no human contact has left him with a rather child-like personality and natural curiosity. When confronted with a butterfly for the first time, Seth simply watched it for a half hour because he had never seen such a creature before. He constantly asks what things are and what they do, further showing his lack of outside knowledge. Seth can also be incredibly caring, as shown towards Spring and the three children he met for the first time.


From a young age, Seth has been known as simply #37, one of but many test subjects that was part of Project Reborn, a program that intended to harness Chaos Magic for unknown purposes. For years, Seth was subjected to torturous experiments that wore on his mind and drove him insane while at the same time imbuing him with powerful magic. By the time he was 19, Seth found a way to escape his bonds and break out of the underground facility he was locked in.

On his way out of the facility, Seth went to great lengths to murder the researchers and release the other test subjects. Afterwords, the only surviving researcher put the word out that Seth was on the loose, and was to be hunted down.


Escape from captivity and battle against Fairy Tail

7 years later

Much has changed in the seven years Natsu and the others were trapped on the island; since he last met up with Fairy Tail, Seth is reported to have lost his sanity entirely, wiping out a town.

Magic & Abilities


Seth utilizing Chaos Magic

  • Chaos Magic - Seth Knighthorn was imbued with a powerful magic known as Chaos Magic, which combines both Light and Dark Magic to create powerful results. With Chaos Magic, Seth can perform unique attacks. When performing Chaos Magic, Seth utilizes Dark Magic energy in his right hand and Light Magic energy in his left, bringing the two together to use his attacks. It is implied that he can use both Light and Dark Magic as well, but is never seen using them. Seth can also transform into Chaos energy, which is useful for dodging attacks or traveling distances.
    • Chaos Shockwave - Creates a blast of glowing light and dark energy that expands outwards in a set direction for massive damage.
    • Chaos Barrier - Forms a barrier of light and dark energy that protects Seth from most forms of attack.
    • Chaos Blade - Creates one or multiple swords made up of chaos energy that Seth can either wield or have fly around him. The blades are stronger than regular swords in terms of striking force but are fairly brittle.
    • Sonata of Yaggoth - Seth calls forth many tendril-like arms composed of chaos energy that attack the opponent.
  • Assimilation Magic - Seth possesses the ability to absorb the cells of his victims. He does this by either absorbing the opponent's cells through his skin or eating flesh (which is his preferred method). While useless on its' own, this power plays a part in Regeneration:
    • Regeneration - Seth can use the cells he absorbs to regenerate from virtually any injury. Even lost limbs can be grown back with enough cells.



For much of his life, Seth has been the subject of various experiments at the hands of MRA researchers. Because of this, he has grown to hate them completely. Seth has never forgiven them for what they've done to him and has amused himself with the thought of killing their members.

Natsu Dragneel

Erza Scarlet



  • "Yaay! I'm going to kill you now! I wonder you what you sound like dying!"
  • "H-hey, what's that thing?"