Lyric discussion by TribeVoice 

It could be that it's about a man who returns to a life of crime.

"Felonius" is the criminal intent and the name of this archetypcal friend

Maye a prequel to "turn that heartbeat over again' ?

But then again it could just mean that he's just reunited with his old buddy that he used to hang with in the old days (a fellow Deacon Blues)

@TribeVoice Thelonius is likely Thelonious Monk, a famous jazz musician.

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