As in any story (and as in life), the characters in Scott O'Dell's Island of the Blue Dolphins make many decisions which affect the entire course of their lives.
A group of natives live peacefully on an island until some Aleutian seal hunters land on the island (the Island of the Blue Dolphins) and want to hunt; the natives allow them to hunt but ask for half the catch. Unfortunately, this was a bad decision. Though the Russians consented to the arrangement, they end up in a fight with the natives over the seals and kill many of them, including the chief.
Later one of the surviving natives takes a canoe and goes for help; this is a good decision, as he is able to send a ship back to the island.
The next life-changing decision happens when the white man's boat comes to rescue the remaining natives (who have been struggling since so many of their men were killed). In the confusion, a young boy named Ramo gets left behind; his sister, Karana, dives back into the water and joins him. Now they are both stranded on the island.
Unfortunately, Ramo decides to leave their shelter alone and is eaten by wolves.
Now Karana has to make all kinds of decisions which can change her life. She decides to escape; however, when she discovers her canoe is not seaworthy, she decides to return.
She decides to befriend the leader of the pack of wild dogs she nearly kills; Rontu becomes her best friend and ally on the island.
When the Aleuts return to hunt otters, Karana decides to befriend one of the Aleutian girls. Because of that friendship, Karana makes many other decisions, though none of these are life-and-death.
After that summer, after being friends with Won-a-nee and her young, I never killed another otter. I had an otter cape for my shoulders, which I used until it wore out, but never again did I make a new one. Nor did I ever kill another cormorant for its beautiful feathers, though they have long, think necks and make ugly sounds when they talk to each other. Nor did I kill seals for their sinews, using instead kelp to bind the things that needed it. Nor did I kill another wild dog, nor did I try to speak another sea elephant.
Every decision Karana and the other characters make shapes their lives--until they make the next decision.