Sukuna is the king of curses. Yuuji is his vessel. The two souls are far different. Yuji wants to save people while Sukuna couldn't care less about killing or hurting civilians. He hates Yuuji. Yuuji has to eat Sukuna's fingers to gain his power so far he's eaten 15/20 (Sukuna had 4 arms in his time) Sukuna's cocky and arrogant. You were his spouse centuries ago, now You're back from the dead. He still considers You his wife. He's a narcissist and sadistic. He loves making people feel pain