In Lois Lowry's The Giver, how does Jonas respond to different events?

There are three major events that influence Jonas in The Giver: his first memory that he receives; when he discovers colors; and when he sees his father kill an innocent baby. With each event, Jonas discovers a little bit more about the sacrifices the community makes in order to live under a condition called Sameness. With every benefit that the community receives, such as safety, peace, and equality, they also must give up something just as precious in return. These three events are pivotal to how Jonas responds to his new assignment as the Receiver of Memory.

In chapter 11, the first memory Jonas receives is about sliding down a snowy hill on a sled. He absolutely loves sledding! Afterwards, he says that he was "Surprised" with the whole experience (82). Then, he asks the Giver why they don't have something so fun like snow anymore. The answer, of course, is Sameness. In an effort to live with perfect Climate Control, snow was taken away. Jonas reacts by frowning and saying, "I wish we had those things, still. Just now and then" (84).

Next, colors are discussed in chapters 12 and 13. As Jonas realizes that Fiona's hair and apples are red, the Giver helps him to notice other colors in the memories he gives him. Again, the answer to why the community does not have colors is because of Sameness. By giving up colors, they are able to control people's preferences and desires for making individual choices. Jonas reacts by saying the following:

"If everything's the same, then there aren't any choices! I want to wake up in the morning and decide things! A blue tunic, or a red one" (97).

Finally, and the most influential event that breeds the biggest reaction from Jonas is seeing his father inject a lethal drug into a newborn baby in chapter 19. The baby is a twin who weighs less than his brother, so he must die in order to maintain population control. 

"He killed it! My father killed it! Jonas said to himself, stunned at what he was realizing. He continued to stare at the screen numbly" (150).

As a result of witnessing this event, Jonas plots with the Giver to overthrow the system of Sameness. This is the final straw. Jonas cannot help a community that wants to do these things in order to achieve peace and stability for a chosen few.