I am not sure if it has been done before or not. It probably has.  But my 
suggestion is go ahead and write it.  If someone gets upset, then so be it.  
Its always interesting thought o see more than one person take on a given 
topic, because even if it starts fron the same basic idea two diferent writers 
are going to come up eith two totally diferent fics.  So I say go ahead and 
write it.  If someone complains, oh well, they'll live.