Develop a musical piece incorporating the designated alphabet-based pattern and the supplied melodic theme.
X:1
L:1/8
Q:1/4=120
M:4/4
K:Emin
['B,2 D2']  
X:1
L:1/8
Q:1/4=120
M:4/4
K:Emin
"^Slowly" D | B,2 D2 (EF)(GD) | E2 E2 e3 d | cdcB AGAB | G2 D>E D2 ED | B,2 D2 (DE)(GD) | 
 EDEG e3 e | dege dBAB | G2 E>F E2 ::  