Dad often has the family do the "skedaddle" and while he claims it is because FBI agents are after them, Mom says that it is actually to avoid bill collectors. Dad is a whiz at math and engineering, but he has no interest in keeping a job for long, so the family shuttles between small desert mining towns in the southwest.
Because of their nomadic lifestyle, Jeannette and her siblings do not attend school regularly. Mom teaches them to read and Dad teaches them math as well as various survival strategies, such as gun shooting. Jeannette loves the desert and compares her family with the cactus plants that fatten up after a rain — like cacti, her family has to take what it can when it can in order to survive.
Dad, in addition to being able to talk himself into nearly any engineering job, is a wonderful storyteller and, more problematically, a drinker, which sometimes fuels the family's wayward existence. One of his favorite stories to tell is his dream of the Glass Castle, a home he plans to build his family, entirely made of glass, as soon as they are able to find some gold and strike it rich.
Jeannette's parents met in the desert years ago when Dad was still in the Air Force. They met while diving off a cliff into a lake forty feet below, both mesmerized by the other's tenacity. In addition to their living children, they also lost a nine-month-old daughter after Lori was born but before Jeannette's birth. After the baby's death, Dad's moods grew darker and he turned more frequently to drinking, although he maintains his dream of the Glass Castle.
Through the metaphors of the cactus and the Glass Castle, Walls provides insight into her childhood as well as her family, particularly her father's characterization. First, in comparing her family to the cacti that load up with water after a heavy rain, Walls shows us that her family is also tough, prickly around the edges, and resilient. Walls follows up this metaphor with examples of her family's feasting on cantaloupe or grapes for weeks. This is resilience in action: The family takes what it can get and does not begrudge the lean times.
The metaphor of the Glass Castle works to explain both her family's lifestyle and to provide further insight into Dad's character. First, the idea that someday the family will strike it rich and live in a house made entirely of glass, with its own power sources, suggests a faith in and desire for future stability despite the lack of it in their current lives. They believe this dream not only because Dad believes in it, but also in hopes that if he focuses on the Glass Castle he will be able to overcome his alcoholism in order to actually make it a reality. However, the very fragility of the dream — the house is made of glass, which can shatter, after all — suggests its elusiveness. Dad, plagued by the loss of a child, paranoia, and alcoholism, is incapable of achieving the dreams he proposes, even though he verbally maintains faith in a different, more prosperous future for himself and his family.