Vengeance
What's the soft spot in your heart that could be targeted by someone seeking vengeance? For me it's our dog. Our dog who bestows nothing but love and happiness onto all that she meets, and who deserves no bad days.
I'm a level-headed big dude and feel the pressure to use my attributes to correct imbalances and bring calmness when things get heated. But despite that, if the aggressor in the situation learned where I live, had no love for animals, and targeted my dog as a revenge method I would shrink to the size of a mouse. Those thoughts can paralyze me with fear and have, at times, made me turn around and go pick up the pup from home...just so I knew she'd be safe.
So my greatest fear? Someone finding and exploiting one of the few soft spots I have in my heart.