What almost happened to Brian and Jeannette at the dump? Why was Rex not upset about it?

Question

This question is from actively learn a glass castle

Answer 1

Brian and Jeannette go to the dump and collect hazardous materials to use as science experiments. They take these back to an abandoned shed and use matches they took from Rex to do their experiments, which causes the shed to catch fire. Jeannette escapes but has to have Rex save Brian, who is trapped. Rex simply explains to them that they got too close to the "boundary" of the fire, almost using the fire as a learning experience for them.