I can so relate to both of your posts, thank you.
I too have an amazing ability to disassociate from danger when it relates to me - I do not react, I feel nothing, I have no fight or flight response, I am numb.
Compare that to danger / distress that affects my dh or my two children, both when they were babies and now as teenagers. I go into full heightened fight or flight mode - I am ready to fight tooth and nail to ensure that they are safe, secure and happy.
The role that follows my numbness is usually that of caretaker - deal with the problem, make it right, can I help, what can I do to sort things, smooth things over so that they return to "normal".
Says an awful lot about the alcoholic chaos and violence that I was conditioned to survive in as a child.