When my son was born, my cat Myrtille became extremely anxious. She never offered to hurt the baby - she loved my son - but she started to lick herself bald in some spots. She never overcame her anxieties, even though she grew close to my son as he grew up. We just had to keep being very loving to her, and accept the fact that for her, the world had changed forever and she would never get over it. Thank goodness, though, she was not violent toward him or her cat foster sister Tzigane. Good luck in finding a way to calm your Ninja's behavior.