More than the harsh demonstration of his weakness, Nero was alarmed by his mothers sudden hug, and show of emotion. Although Irene could not be called an outsider, it wasn't as if they had spent much time together as a family. Marilyn was very particular about showing affection in public - in such matters she was very private.
His mind could not help but go to all the danger he had faced, not just in Lumina, but in Perilith as well, as he hugged her back. His parents, too, must have faced such similar dangers in their life as they grew up, which is why they had prepared Nero and Patrick so well. Even so, they could not help but worry.
In truth, because of how limited his exposure to actual missions was, and how extreme that limited exposure was, Nero's perception of what the average soldier experienced was extremely skewed. How could a normal soldier go through the kings he had and come out unharmed?
