Once, Fu-xi was a brave and noble warrior, regarded by many snakes as a hero and treated like a lord. Fu-xi defended others with his incredible skills and fear-inducing venom. But when others regarded him and his kind with paranoia and hate, Fu-xi changed for the worst, taking on a racist hatred towards "two-leggers" in retaliation for their violence and persecution.
He came to view himself as a defender of serpents, considering the ones that went along with him as his brethren, but having expectations of his kind, saying they should be strike fear into "two-leggers", and to be prepared to strike at them by any means necessary.
Fu-xi fights with a very similar style to Master Viper, with lightning fast moves, but he also incorporates biting to deliver his fear-inducing venom into his opponents/victims.
Role in the series
Fu-xi saved Viper from some paranoid villagers who attacked her simply for being a snake, and revealed he'd heard of her, the "Great Master Viper of the Jade Palace", addressing her as "little sister", for in her he saw a potential ally/apprentice. He subtly demeaned her a few times for fighting for "two-leggers", trying to convince her she should fight against them and side with him. Fu-xi regarded Po as just another "two-legger" to get rid of, and used his unfavorable comments about snakes in efforts to sway Viper to his side, and he violently tried many times to kill him. However, trusting Viper just for being a fellow snake proved to be his downfall. Aside from seeing his defeat of him getting unconscious, his fate is not exactly, clear, and it's not yet known, though not doubtful, that he would return.