the piano

So I've been thinking about all the different elements of the  book and a huge part of  it is spent talking about Billie Jo's relationship with piano and how it affects her life and in the beginning of the book her piano is a positive thing in her life and after her mothers death she tries to block it out of her lifeQUOTE:(pg 87) "its hard to believe I once brought money in too,even if it was ust a dime now and then, for playing piano.Now I can't hardly stay in the same room with one. especialy Ma's"  (shes scarred by it 'cause  it is her mothers piano and you know what happened)but I'm still trying to figure out what Arley Wanderdale and Mad Dog Craddock contributed to the plot besides fueling Billie Jo's wanting to leave and her passion.What do you think Arley Wanderdale and Mad Dog Craddock contribute to the plot?