Empathy?

Last night Luke was sick and threw up many times between about midnight and 2am. Henry was awake most of that time, but each time I was out of bed helping Luke, he stadyed strangely still and quiet on the bed. When Luke settled back down to sleep and I got ready to return to bed, Henry would start to fuss a little. It seemed like he knew that Luke needed my help. It hardly seems possible, but it happened about five times.