To keep a regime built on strength running, you need to be strong or project strength. Doesn’t matter if its fascism or communism or to some degree even a democracy. Mussolini was sour Hitler did everything he did, but better and with more resources. Hitler just considered him his prototype who paved the way for him. Mussolini had no choice but to become “Hitler’s bitch” since he already burned all bridges with everyone else due to Ethiopia. It got so bad in the end that Mussolini was happy when he was arrested and imprisoned, and horrified when Hitler freed him and put him back in power. He was long since over that life at that point.