Why does Palmer choose Henry to invite up to his room to prove Nipper is no longer there? What happens between them when Henry is in Palmer's room?

Palmer has always felt Henry was different than Beans or Mutto. He believes Henry is gentler than the other two boys. He knows his mother will not let the gang into the house, so he brings only Henry in when his mother is not home. While in Palmer's room, Henry avoids Palmer's eyes as he looks around the room and under the bed for signs of Nipper. Palmer tries to start a conversation by asking Henry his real name, but Henry only replies "George" and quickly leaves the room.