So, in this AU, Mary never had any other children and Edith never met Bertie. The year is 1945, and Mary has recently passed away. Since she was the last person living in Downton with her son, the place is abandoned now.
Lady Edith Crawley entered her room. She lived mostly alone these days, with no other company than that of her butler, a housemaid, and a cook. Even ladies dressed themselves these days (As she had suspected from the start of the new ordeal, two wars were too much for the ancient customs of the British aristocracy to bear), so she had no need for a Lady's Maid. Surely, Sybil Branson, George and Marigold Crawley also lived in 35 Belgrave Square, a house which used to belong to her aunt Lady Rosamund, but they were new additions, and hardly ever interacted with the bitter redhead.
That day fitted into the "hardly ever". George Crawley, a short and slim-framed 25-year-old man, entered the room covered in snow. He had the light-footedness attributed to his mother Mary, who died a few months a
go, bless her soul, but reminded Edith much of Matthew Crawley, the previous heir of Downton, with his light blonde hair and blue eyes, although otherwise his features resembled her late sister's.
"Good day, George" Edith said, in a deadpan tone. She had barely sat in her bed at the time George arrived. He hardly made any noise walking, an attribute befitting of a lady, but not of an adult man like himself.
"Good day, Aunt Edith" The man announced
"I hope you invaded my room unannounced and uninvited for better reason than simply wishing me a good day"
"I have in fact" He started fidgeting, something he did when nervous. George had wanted to fight in the war, although he didn't due to Mary pulling strings and connections. Edith was glad her sister did so; George would've been claimed by shell shock or something even more terrifying, if simply talking to his now legal guardian made him fidget that much. "I wanted to visit Mama's grave"
"And what is the reason to such demonstration of grief?"
"Well, it's the first Christmas I spend without her, Aunt Edith"
"And what is so special about Christmas that makes you need to visit your mother's grave when you showed no desire of wanting such a thing yesterday?" Edith reprehended him, but continued "There's some money in my desk. Take it a pick up a train to Downton village. And please, on your way out, inform Marigold and Sybbie that I have a terrible headache and that I will get some sleep to see if it does any good"
"Thank you, Aunt Edith!"
She didn't answer.
Edith woke up late. It was nighttime already, and she had been awoken by the sound of a knock in her door. Marigold and Sybbie entered the room as soon as she instructed them to come in.
"Mother, Lady Rose asked us to inform you that she's throwing a party at Downton Abbey. A Christmas Eve party. You might want to come" Marigold pronounced.
"Do not announce your position as my daughter so loudly. Ever. It was a mistake to ever tell you" Edith spoke, harshly "And no, I do not want to come to silly Christmas parties thrown by silly marquess' daughters. Tell Lady Rose to go and..." The older woman stopped herself mid-sentence; she may have been bitter but she had enough care for etiquette not to insult a relative in such a ghastly manner.
"Can I come though?" Marigold asked hesitantly.
"No, Marigold. You are my daughter, and I shall make sure to telephone Lady Rose and tell her to stop inciting my own daughter into abandoning me" She said with a disapproving face.
Marigold and the silent Sybbie left the room.
Later at night, Edith heard a noise. A noise that couldn't have been made by the two girls. A noise of chains...
