How did the giver changed throughout the novel and what caused the change?

The Giver has long been a integral part of the community. He has held the memories and performed his duties as expected. None-the-less, the experience of losing his own daughter to her requested release has ultimately changed him, just as his current situation with Jonas changes him even more. For years, the Giver supported the community. His relationship with Jonas makes him realize that his knowledge and support can change things within the community.