I never liked her. She and Edith were both kind of nasty at first, but Edith mellowed out. Mary briefly humanized with that milksop Matthew, but once he died... the guy she is romancing now (the one who was going off for a year) is up to her speed, I think, and can handle her.
Charles Blake? I definitely liked him more than Lord Gillingham.
Wonder if they'll kill off the dowager this season? I hope not.
Dame Maggie Smith figures that Violet must be about 110 now. She's only off by a little bit. Violet was born in 1842 (according to the Downton Wiki), which makes her 82 in the fifth season, which makes her two years older than Dame Maggie.
I expect a major death or two in season six (just because there hasn't been one since Matthew -- and, no, I'm not counting the dog), but not the Dowager Countess. She is a survivor.
I kinda thought that Downton would end with Robert's death. Maybe he's out walking his next dog, Osiris, and he has a heart attack on the grounds.
I don't remember if they showed or had a character state why Mary is such a bitch when it comes to having even the tiniest scrap of consideration or compassion for Edith.
I remember, vaguely, something in the first season, maybe even in the first episode or two, while they were all mourning their cousins who died on the Titanic. Mary was engaged to the cousin, but it was Edith who actually loved him. Edith said something to Mary like, "Whatever I want, you take." And I seem to recall that when Edith started showing an interest in Sir Anthony Strallan, Mary decided to make a play for him, just to mess with Edith.
I don't think there's any particular reason why Mary is so horrible to Edith. Certainly Edith's decision to reveal to the Turkish ambassador what happened between Mary and Kemal Pamuk threw poison down the well, but that well was already well and truly poisoned. From the vantage point of the fifth season, in retrospect that move doesn't look now like the bitch move that it did at the time; you look at where the Mary/Edith relationship has gone and is now, and you see that there's only so much abuse one can take before they lash out. It's a wonder that Edith hasn't done more to Mary.