Create a composition by utilizing the given alphabet-based musical pattern and the provided melodic theme.
X:1
L:1/8
M:12/8
K:C
['A2 G']  
X:1
L:1/8
M:12/8
K:C
 cBc A2 G EAA GED | ECC GCC EDD DEG | cBc A2 G EAA GED | ECC GCC EDD DEG | cBc ABc Bdc BAG | 
 cBc Adc BGG G>cd | ece dBd cAc A2 G | E>AA GED ECC C2 ||  