(I've had the basic idea of this running around my head for awhile, so I'm typing this out to get it out there, it's not a story yet but a rough idea. I'm not typing EVERY idea out here, some things have to be a mystery hmm?? Naturally it's Mary Bennet-based. Mary may or may not have a twin brother in this, I'm not sure yet.)
Mary Bennet always feels over-shadowed by her 2 younger sisters and her 2 eldest sisters, so she focuses on what she loves most, her music. She practices nearly every spare moment she has (when she isn't reading or writing for that matter) until her mother threatens to throw out her precious keyboard Her paternal grandfather bought if for her when she was younger and felt she had promise after she was constantly caught noodling on her late-grandmother's piano. Her sisters nor her mother don't thank him for it, her father is just simply amused by his wife's reaction.
Pre-P&P: She is offered a job making instrumental piano versions of popular songs (she was discovered on youtube doing just that, under a stage name which she continues to use) which she takes (she uses an actual piano at the studio she records at, and uses her keyboard to compose and tweak it but uses a real piano to listen to the final product and to make any tweaks if needed) and even writes and performs her own compositions (which turn out they're quite popular)
Then the plot of "Pride and Prejudice" happen though just a bit modern-ified, but during that Mary's mother (the morning after the Netherfield party) after hearing playing one too many times for her liking she yanks the keyboard from her, demolishes it and tosses it into the garbage, Lydia (Olivia) laughing all the while and Jane looks horrified for Mary, Lizzie looks indifferent and a bit relieved (none knowing that she needs that keyboard in order to help her do her job). Visibly upset she runs upstairs to her room and locks the door. She cries but not so anyone can hear.
(It's so hard NOT to write this story right here and now!)
Eventually she gets another keyboard top of the line because with all the money she's making with her work (her family doesn't know what her job is, Jane might suspect) she can afford it but she is saving up for a place of her own but she's keeping that secret too).
Skip forward to the end (for now) After most of the story is over Mary catches an earful about the new piece of music Georgie is working on (Georgie still loves the piano in any universe) in a conversation between Lizzie and Darcy (Mary is hidden from their view). They both talk about how beautiful and elegant the piece is (one of Mary's favorite of her own compositions) and how even Georgie is having a little bit of difficulty in learning it (Georgie is always up to the challenge claims Darcy)
Out of nowhere (it seems to the happy couple at least) Mary starts giggling before she comes out of hiding, thanking Darcy and Lizzie for their excellent taste in music. Mary wrote that particular piece in a moment of pure happiness. When Lizzie didn't believe her (Darcy stood there looking as if he didn't know what to think). Eventually to prove her claim she pulls out her keyboard and without the sheet music starts playing the piece in question with ease. Since the piece was just released just a month ago, no one could master it so quickly, at least not well enough to play it without sheet music.
But there was Mary playing it as if she had played it every day of her life
I'm going to stop here for now I'm wiped out and I need to sleep. Maybe more notes later?