As a rule, a certain period in my life is marked by a certain emotion. Happiness changes sadness, energy comes after frustration and so on.
A very long time ago I noticed that anger goes hand in hand with fear. Let me make my point clear. When I felt anger for a number of days, I knew that after that fear would come and vice versa. Sometimes it felt like a vicious circle from which it could be rather difficult to disentangle myself. At other times I was gripped by the two emotions simultaneously: I might behave aggressively feeling fear inside or, on the contrary, showed fear and meekness while feeling anger. All this made me wonder, for I couldn't approach understanding the mechanism.