It's been a while since I was writing it, but I think I was trying to do some sort of distorted parallel between Lady Middleton/Caroline and Caroline&Georgiana, since Caroline's mentally cast herself as a mentor-figure to Georgiana, albeit not a sexual one (though she has been tempted.)

Oh, and I think probably another reason I ended up using Lady Middleton is that even though she is not made of raw femslash potential like Emma and Mary Crawford, my slash goggles had previously given me thoughts of Lady Middleton/Lucy Steele.