First love
It doesn't hit her at first, the crippling love she feels later that she covers up with scorn, but it comes soon after.
Sarah thought she'd been in love before, with a miner with bright blue eyes, rough hands and a heart made of the brightest gold, but it was never like this. She never lived for Mickey's smile, she never hung on his every word. She supposes it's her job to listen like every word is gospel but it is to her, and that's the most pathetic thing of all.
She lets the others believe she hates her, and sometimes she thinks she does. Her voice grates, her gaze burns and sometimes she's so bloody up herself Sarah wants to strangle her. But then she calls her dear O'Brien in that bleedin' purr of hers, and she knows she could never hate her. She despises herself more than she does Cora Crawley for being so bloody weak in the first place.
She's not the first to fall for those big blue eyes and all that American charm, and she certainly won't be the last. But not one of her other admirers spends every day beside her, bathing her, undressing her and tending to each and every one of her intimate bloody needs; she knows she should get out while she still can, while she's young and still has prospects. But year after year she remains, despising and adoring her until ten years have passed – the most miserable, wonderful years of her life – and she's even more captivated than ever.
Sarah isn't sentimental enough to believe in fate and all the rest of that bollocks, but she's realistic enough to know she never loved Mickey, at least not enough to let him take her down the aisle.
Cora is her first real love, and god help her, she'll probably be her last too.