Eric's growth through his development of empathy is best conveyed when he reflects on his mother's loneliness and the things she has done for him.
The detail that best conveys Eric's growth through his development of empathy is when he thinks about his mother's loneliness and the things she has done for him. In the passage, Eric reflects on how his mother cared for him when he was injured and protected him from being scolded by his brother.
He realizes that his mother's unkindness was small in comparison to her loneliness, and he feels a deep love and understanding for her.