My son is an extroverted feeler. He was about four when we were reading "Where the Wild Things Are" and he burst into tears.
"What's wrong?" I said.
"The Wild Things! Max is mean! He sent them to bed without any supper! They're hungry. They are sad! He is mean!" wailed my son.
"They were rioting around, after all."
"He shouldn't make them be hungry. That's not right." said my son fiercely.
He either had not noticed that Max was sent to bed without supper or thought it was deserved. On the other had, Max did get his supper by the end of the book and the Wild Things didn't. A loose end in the book that my son did not like.

Another time he asked about eggs.
"Where do eggs come from?"
"They are chicken eggs."
He looked worried so I hastened to reassure him. "They don't have baby chickens in them. We have eggs that only have a mother chicken involved and there isn't a daddy chicken involved. You have to have a daddy chicken before you have a baby chicken in the egg." I realized I was getting into deep waters and with a bit of an effort stopped. My son did not look like he was done with the topic.

He thought for a bit.
"Do the chickens give us the eggs?"
Not what I was thinking about! Change gears, mom. "Um, no. We take the eggs from the chickens."
I could see that this wasn't very nice of us. More thought.
"Do chickens eat people eggs?"
Oh. Fair is fair, right? "Um, they would if they could. People eggs are inside and people don't lay eggs like chickens. The eggs turn into babies inside. Sometimes. The eggs don't come out," (well, actually they do, don't they? Didn't seem the time to try to explain menstruation). "But if the chicken was given a people egg the chicken would certainly eat it." At least from the little I know about chickens.
That was satisfactory. He returned to eating his egg.

And that is how my extroverted feeler son demonstrated empathy at age four.