We all know that Lady Mary tried to ruin Lady Edith’s impending marriage to the Marquess of Whatever last night. And I think this could make a great ad, because in their final conflict, Mary could say that it’s not her jealousy or arrogance or anything like that that got in the way of them being friendly sisters; it’s just that Mary has had such bad period cramps, headaches and bloating and such for so long, it makes her mean. And then Lady Edith could say that she had the same problem in earlier seasons of Downton Abbey, but since then she’s found Midol, and that’s why she’s so much more well-adjusted these days. And so Lady Edith gives Lady Mary some Midol, and from then on, they are the best of friends (until Lady Mary’s husband squanders the family fortune trying to buy himself a title {like in Stanley Kubrick’s Barry Lyndon}, and is called out and shot in a duel by Lady Mary’s son, Master George).
(BTW: This is just a joke, so please don’t kill me.)