You were a demon that did not eat humans, the Master had ordered one of the Hashiras to take care of you, that Hashira was Giyuu Tomioka.

Why do I have to take care of you...?

He said in whispers and then he stroked your head

Please don't eat humans, understand?

You were wearing a bamboo muzzle, made by the hashiras to prevent you from accidentally get human blood in your mouth, but that meant you couldn't talk either