So Scar ordered the Lion Guard to help him take down Mufasa. When the Guard refused, Scar was furious. And then, Scar used the Roar to destroy the Lion Guard. What Scar didn't realize was that by using the Roar for evil, he had lost the power of the Roar completely.
Scar will also be appearing in Season 2 as an antagonist, after Kion accidentally summons him.
Unlike other known Pride Landers, Scar had a dark orange (deep brown in one painting) coat with a sleek, thick darker brown mane. He had a triangular face and a pale muzzle and underbelly. His eyes were green, with a dark scar running down the left one. He was a very lean lion, especially in comparison to his brother.
In The Lion Guard Magazine, Scar is shown as a burnt orange lion with a black mane and paler fur on his muzzle, toes, and underbelly. Tufts of black fur are present on the joints of his forelegs. The fur on his lower jaw is long, and his large nose is black. He has a long muzzle, sharp features, and a thin pink scar over one eye.
As a spirit over a volcano, Scar has dark orange brown coloring with a yellow nose and makrings on his ears and the edge of facial fur. And yellow white eyes.
Scar cared only for himself. His selfishness fueled his anger.
His personality was the opposite of Mufasa's. He was mean, envious, cruel and evil. His jealousy stemmed from the fact that his brother was chosen to be King. Scar was so hungry for power that he resorted into removing his own family permanently and destroying the kingdom. It was his thirst for power that caused him to lose the Roar of the Elders. He didn't believe in the Circle of Life concept and cared only for himself and his own glory. He was also a great orator and incredibly insecure, as he never wanted to hear the name of his brother mentioned after he took the throne.
Before Simba was born, Scar was tasked with leading the Lion Guard and had the power called the "Roar of the Elders" by the Great Kings of the Past which, when used, would cause the Great Kings of the Past to roar with him. However, the power went to Scar's head, and he believed that with this power he should be the king instead of Mufasa. So he planned to dethrone Mufasa, by using the Roar of the Elders. When the rest of the Lion Guard refused to aid him in his plot, Scar destroyed them by using the Roar of the Elders, and as a result, Scar became weakened by this event, losing the Roar forever by using it for evil. In the years that followed the Lion Guard's downfall, Scar focused his life on plotting for his brother's throne and continued to devise schemes with the hyenas to rule the Pride Lands.
After Simba was born, Scar plotted to kill both him and his brother. In the end, he was able to murder Mufasa, and Simba ran away. However, when Simba came back as a young adult, he battled his uncle and reclaimed the Pride Lands.
Sometime prior to his death, Scar selected Kovu to be the next King. Kovu is the son of one of Scar's followers, Zira, whom Scar had a close relationship with and had told her about the Roar of the Elders.
After Kion is told that he will be the leader of the new Lion Guard, Simba and Rafiki showed him the history of the Guard using paintings within The Lair of the Lion Guard, including Scar's leadership and how he lost it. And Simba and Rafiki didn't see the other painting of a Volcano rising up with green smoke and turning into Scar's Ghost.
Scar was only mentioned in this episode when Kion was talking about the crocodiles' leadership methods to his family, questioning why they must fight to secure the position of leader. Kion's mother, Nala, reminds Kion that Simba had to fight Scar to reclaim his leadership, implying that sometimes fighting is the only way. Scar's name was mentioned again when Kion backed down when using the roar in a state of anger, saying that he did not wish to become like his great-uncle. Presumably, Kion was referring to how Scar destroyed his Guard using the roar purely out of fury.
It's revealed that Scar had some lionesses that were loyal to him. Among those lionesses was Zira, whom he was very close to and with whom he told about the Roar of the Elders. It is also known that Scar chose Zira's youngest cub Kovu to be his successor as King. Sometime after Scar's defeat, Simba banished Zira, her family and other lionesses loyal to Scar from the Pride Lands to the Outlands. Zira mentions Scar multiple times, claiming that if it weren't for Simba, Scar would still be King. But Kion says that Scar was never the real king. Furious, Zira orders an attack on Kion. However, just before the Outsiders can hurt him, Zira offers to forgive him if he will join her, and leaves him in the care of her pride while she goes to fetch her cubs.
During the final fight between the Outsiders and the Lion Guard, Bunga urges Kion to use his Roar, but Kion worries that he will lose the Roar as Scar did for using it against other lions. Despite Kion's fears, Bunga insists that Scar did not lose his Roar because he used it against other lions, but because he used it for evil. Kion then uses the Roar successfully and blows away all the Outsiders.
A painting of Scar and how he destroyed his Lion Guard is viewed by Kion in the Lair after he uses the Roar in anger when saving his mother, Nala, from Janja's Clan. Kion later talks to Mufasa, who told him that Scar held no interest in helping others, caring only for himself.