During her three seasons with Downton, O'Brien was a perpetually grumpy presence downstairs. She was Thomas Barrow’s best frenemy. She was a dastardly placer of soap.
Never one to make friends easily and then only for her own benefit, O'Brien always put O'Brien before others. So perhaps we shouldn’t have been surprised when she “snuck off like a thief in the night” as Robert put it. Her destination: India with her new employer, Susan MacClare, the Crawley’s Scottish relative and mother to their visitor, Rose (Lily James).
Cora was baffled that her seemingly trustworthy lady’s maid (oh, Cora, what a bad judge of character you are) would leave her without warning while, downstairs, Thomas was left without a sparring partner and fairweather ally. But could O'Brien return as quickly as she left?
That’s doubtful as the actress who plays O'Brien has voiced no interest in returning to the show. Plus, if O'Brien did return she’d be in some hot water. At the end of Season 3, Thomas let the lady maid’s soapy secret slip to Mr. Bates (Brendan Coyle) and even though he may not know the full story, the street-wise Bates knows enough to get his nemesis into trouble if the right situation came up.
So, to make a long story short: Don’t expect to see O'Brien’s curly forelocks back at Downton anytime soon. Instead, she’ll be off in India sweating through her all black wardrobe.