Copper Lightvale

Copper Lightvale, the Wizard of Determination, was one of the seven wizards who sealed off the Underground. He was the twin sibling of Agate and the older brother of Amber. His mother died after giving birth to Amber, and his father's death is unknown.

Appearance
Copper has a long-sleeved, pastel pink shirt and shorts of the same color that almost reached his knees. Like Frisk, he had brown, medium-length hair and red eyes. His armor had golden pauldrons, grey faulds that were partly gold near his hips, and a grey cuirass. He had three golden triangles, which resembled the delta rune.

Copper also wears a brown sweater with a pastel pink stripe in the middle, brown shoes, and brown pants.

Copper's Determination Trait
It is known that he is the strongest wizard, because of his DETERMINATION trait, which is known as the strongest and rarest SOUL trait. Also, it is unknown why, but a common fact of this trait is that DETERMINATION SOULS tend to seek peace between humans and monsters.

Copper was extremely powerful, even at a young age because DETERMINATION would never get corrupted, and would never grey. This is exactly why his death shocked the entire kingdom under his command. The exact reason why he lost his magic in the middle of the fight, as well as the circumstances behind his death, were unknown to the rest of the people under his power. But in Glitchtale Origins... The Black Beast, we learn otherwise.

Personality
He is willing to go great lengths to protect his family members, such as deciding to fight Agate and possibly die in hopes of protecting Amber. He also didn't want to fight unless it was absolutely necessary. This was shown when Agate wanted Copper to fight her, but he refused until Amber's safety was threatened in Glitchtale Origins... The Black Beast.

Copper was also quite kind and merciful, shown when he spared Agate after he defeated her at the end of their first battle and [|here].

Copper, correlating to his SOUL trait, is likely determined to accomplish his goals and never was inclined to give up.

He experienced extreme levels of despair that caused him to lose his trait when he witnessed Amber getting brutally killed by Agate. Unable to fight because of his lost trait, he himself was brutally murdered in one blow, without fighting back.

Unlike his sister, Agate, Copper believed the barrier should not have been established in the first place.

Glitchtale Origins... The Black Beast
This episode as of now has managed to provide the most detail on Agate and Copper thus far. This begins with Amber's birth, where Copper and Agate watch the scene, and witness their mother die after giving birth to Amber. Thus, Agate and Copper raise Amber along with them and discover along the way that she had a special green and blue soul.

Later, when Amber turned four, the two became closer to her than ever. However, things began to change once the two siblings began to argue over the barrier. This eventually led to them battling, with Copper winning. Agate's loss humiliated her, causing her to lose her trait and making her flee. During the time period when Agate left the kingdom, Copper was left to rule the kingdom on his own. He struggled and became stressed over his multiple responsibilities. Meanwhile, Agate searched for another soul trait that was more powerful than DETERMINATION so she could defeat her brother during the next battle. Later, Copper and Agate finally reunite. However, something seemed different about Agate this time around.

After time, she challenged her brother once more by sheer force. This time, however, she began to win during the fight. Eventually, Agate killed Amber, causing her brother to despair and lose his trait. With Copper in this state, Agate murdered him as well.

Agate grabbed Amber's corpse and dragged it to a different place. There, she performed the "Bêté Noire" spell. She turned her soul pink and used Amber as a vessel for it. With her SOUL safely in Amber's body, she died and created Bete, a creature whose sole purpose is to make sure that humans and monsters would never have peace with one another, was created.

Dust
After discovering a book about ancient human history, Dr. Gaster discovered the story of Copper and Agate. However, he was having some trouble. This was because the runes they used were so ancient he could not decipher it, as the book was in inadequate condition. Dr. Gaster continued to read this as Asriel and Sans went to the Anti-Monster Department building. However, by the time he read the information that leads him to conclude that Bete was murderous and not the kind, caring being she claimed to be, it was too late for him to go to the AMD, because shortly after reading this, Bete stole Sans's SOUL.

Trivia

 * Agate Lightvale and Copper Lightvale came from the beginning of Undertale, where we saw a wizard with a sword and a wizardess with a spear.
 * In Glitchtale Origins... The Black Beast, the Lightvale mother's trait is Integrity.
 * Tumblr user "mya-arts" has found the meaning of the names. Copper alludes to the metal "copper," which is reddish-brown (which is used in Copper's hair and SOUL trait), has very high conductive qualities. It is believed to give energy/mental agility to those who use it. Meanwhile, Agate alludes to the color "agate," which is believed to contain balancing/ yin and yang powers. It is also believed to help calm emotions, clear the mind, release negative energy, and ease stress by clearing phobias and fears.
 * There is also another mineral named Copper Agate.
 * Copper's father died before the Human and Monster War.
 * If Agate used Copper as the vessel for the Bete Noire spell, the spell would've been much stronger than the currently known Bete. However, Agate was so bitter with Copper that she couldn't bring herself to do the spell on her brother.
 * Agate and Copper's incident took place ten years after the creation of the barrier.
 * If it hadn't been for Copper's DETERMINATION soul, the Lightvale's wouldn't have been a noble family.
 * Before Agate and Copper fought, Agate was jealous of Copper since he possessed a Determination soul, a trait that she knew she couldn't overpower.
 * Agate and Copper killed the most monsters during the war out of all seven wizards.
 * Copper and Agate were in charge of a small city in the middle of the continent. As seen in this picture.

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