Develop a musical piece using the given theme and incorporating the letter-based structure provided.
X:1
L:1/8
Q:1/4=140
M:4/4
K:G
['G2 DE G2 e2', 'G4 d2 Bc d2 g2 fafd cedc']  
X:1
L:1/8
Q:1/4=140
M:4/4
K:G
 G2 DE G2 e2 | dBAG AFED | G2 DE G2 e2 | dBcA G4 :| d2 Bc d2 g2 | fafd cedc | B2 GA B2 ^c2 | 
 dfe^c d4!D.C.! |]  