I think that it's a metaphor for his little brother being on drugs. Just discovering rock n'roll is slang for just getting into drugs. His brother is obviously an unhappy, troubled person ("how's he living / with all that unforgiving" and "why don't our parents worry about us") and Eddie is showing his sympathy and support for him. An educated guess, considering the improv parts I've seen Eddie perform during live versions of the song.
I think that it's a metaphor for his little brother being on drugs. Just discovering rock n'roll is slang for just getting into drugs. His brother is obviously an unhappy, troubled person ("how's he living / with all that unforgiving" and "why don't our parents worry about us") and Eddie is showing his sympathy and support for him. An educated guess, considering the improv parts I've seen Eddie perform during live versions of the song.