Mirror, Mirror (Ron/Pansy, Hard R/NC-17), by
eonone "Each twin had a different theory as to why the small corridor was there. Fred, ever the inventive one, said Filch had designed it to spy on the girls- and boys- as they readied for bed or baths or the like. George suspected it was rarely used, put in place by the Founders to keep a close eye that only Prefects, Captains, or those of the respective gender entered each bathroom. Ron didn't care enough to formulate his own theory as to why the small corridor with the windows adjacent to the mirrors of each bathroom was there. He only cared that it existed."
Written for the
smutty_claus fic exchange way back when in 2006, this fic features an incredibly sexy, funny Ron. My goodness - that's all I got to say about this little gem.