He caused the Copper's crippled forelimb in a hatchling fight. He was killed from the Copper crushing his neck while Auron gutted him with an egg tooth. The corpse was eaten by the other hatchlings.
He is the reason that even as an adult AuRon refuses to rub off his egg tooth.
Years after his death, his brother (and killer) AuRon decided not to allow his own sons to fight each other, separating them from birth. Also, remembering how they managed to defeat him, AuRon and the Copper eventually would find a strategy to defeat Rayg and Imfamnia during the Second Dragon Civil Wars.
AuRon never regretted the killing of his brother, being aware it was a struggle for survival.