Derry's journey reflects an intense personal challenge that he overcomes through courage and determination. Elaborate. (On The Face Of It)

not just a physical scar but the mental wall of self-pity / self- loathing and isolation he created to protect himself from the insensitive / cruel world Shows courage and determination:

talking to Mr. Lamb makes him gather courage and face his deep insecurities

starts seeing himself as a 'whole person', not just a burnt face / overcomes his obsession with his burnt face

realises his potential and returns to garden / asserts his independence / ready to face the world

determined to live on his own terms - no longer cares what others say but focuses on what he wants, thinks, feels