How does the motorcycle boy explain his brothers fear of being alone?

The motorcycle boy explains his brother's fear of being alone by highlighting that it stems from a deep sense of insecurity and dependence. He suggests that his brother feels incomplete without the presence of others, which amplifies his anxiety. This fear is rooted in a lack of self-identity and confidence, leading him to seek solace in companionship rather than embracing solitude. Ultimately, the motorcycle boy portrays this fear as a barrier that prevents his brother from fully experiencing life and understanding himself.