Who is Raistlin from Dragons of Spring Dawning and what is their importance?

Raistlin is Kit's half-brother and Caramon's twin. He is a mage, who has been disfigured by his use of magic. Raistlin's eyes have become golden hour-glass shapes, and his limbs are frail. Each time he casts a spell, he becomes increasing weak, something that requires he regularly be cared for by his brother. Raistlin is drawn towards evil, but the love he has for his brother overshadows all else. At the start of the novel, Raistlin suffers with a persistent cough that produces blood. Then, he goes through a transformation that makes him strong and healthy, so he no longer needs his brother's help. Because of his ambitions to rule the world and his newly found freedom, Raistlin leaves his brother at the end of the novel.