I have fears, but I wouldn't call them irrational. Fear of heights, for example. Or roller coasters. Especially the upside down ones. People out to get me. Rape. Lots of rational fears.
Oh, and being too weak to defend myself. It's probably why I'll go to the extreme if I'm attacked. I'll aim for the knees first, kicking until they break. Then the groin, kicking until they collapse. Then stomping on the wrist and kicking out the elbow, on both sides. Then the ribs and the head.
I'm only 5'3", so I have to go that far to protect myself. Like a baby snake.
Fear drives my brutality, I guess.