Develop a musical piece incorporating the designated alphabet-based pattern and the supplied melodic theme.
X:1
L:1/8
M:2/2
K:Emin
['GA BcAB GAFG EFGA B2 ef gfed', 'E2 ga babg efga babg egfe d^cde', 'EFGA B2 ef gfed', 'ga bagf efge bege bege d2 d^c']  
X:1
L:1/8
M:2/2
K:Emin
 GA | BcAB GAFG | EFGA B2 ef | gfed edBd | cBAG A2 GA | BcAB GAFG | EFGA B2 ef | gfed Bgfg | 
 e2 E2 E2 :: ga | babg efga | babg egfe | d^cde fefg | afdf a2 gf | edef gfga | (3bag af gfef | 
 gfed Bgfg | e2 E2 E2 ::"^Variations:" GA | (3Bcd AB GAGF | EFGA B2 ef | gfed Bdef | gedB A2 GA | 
 (3BcB (3ABA (3GAG (3FGF | EFGA B2 ef | gfed Bgfg | e2 E2 E2 :: ga | bagf efge | bege bege | 
 d2 d^c defg | afbf afdf | edef gfga | bgaf gfef | gfed Bgfg | e2 E2 E2 :|  