How Much would you risk for a stranger ?

I've noticed that Jonathan is risking a lot of things for a little boy he just met. " He picked up the boy again holding him tightly though his arm ached..." I believe that's something you do out of niceness, but then Jonathan is thinking about killing the Hessian soldiers because he is assuming that the Hessian soldiers killed the little boys parents. I'm not sure if others would be in the position of Jonathan because if you think about it, why help a stranger ? , especially if the stranger hasn't told you their name & doesn't even answer you. Jonathan abseloutly knows nothing about this little boy because he never replys to the questions Jonathan has for him.