A big idea the plot might develop is protecting people from pain can be taken too far. Some of these themes have been expressed already and some are themes I think the novel might express in the end, the Importance of Memory. One of the most important themes in The Giver is the significance of memory to human life. The Relationship Between Pain and Pleasure. The Importance of the Individual.Rules and Control. Rituals.
Hope this helps!!
~Alexis C.