A person who shows respect towards or fears those who are strong, aggressive, always ready to fight when pushed around or something unfair happens to them, but bullies the weak or those who dare not speak for themselves or fight back when treated unfairly or badly. What do we call this kind of people? Is there one word (adjective or noun) for that?
There is a humorous word for this: dastard (not bastard but almost)
A malicious coward; a dishonorable sneak.