Sha Chen was unaware of the thoughts running through Red Boy's mind. Otherwise, he would surely have cried out, "Unfilial son, behold my sword!"
Red Boy, on the other hand, was considering helping his adoptive father sell the Elixirs to alleviate the awkward predicament of his adoptive father's lack of clothing and food. As for how to sell them, could his adoptive father possibly know better than him? No one understood buying and selling better than Red Boy himself. As he pondered this, he was almost moved by his own thoughts.
I am truly a filial son, considering my adoptive father's needs so thoroughly.
