The old man was an obnoxious man, which Dave didn't like much. While on the other hand, the old man's blood, his grandson had a totally opposite personality. After getting the responsibility to gather firewood, the young man started running here and there, working hard, gathering wood.
Eventually, he gathered enough that would last them a couple of hours, so he made him stop. The boy felt sad that he stop. It seems as though he loved doing manual labor. He then started asking for more such jobs where he could help him out.
The young man's enthusiasm was commendable, but if he would have asked him to do some more things, he would surely hear more snarling comments from the old man, so he declined. The young man kept insisting, but he kept declining, eventually, the old man came and took him to the corner and gave him an earful.