Lesbingqiu au where, in the original plot for it, Bingjie would have entered an imperial court as a freshly obtained Consort to the Emperor. Shen Qingqiu (Jiu), the Empress, would take terrible exception to her and make her life hell; and when Bingjie successfully becomes pregnant, Shen Qingqiu does all in her power to make her miscarry. Cue black lotus arc when the Empress eventually succeeds. You can guess what happens later.
In this au, Shen Yuan transmigrates in shortly after Luo Binghe joins the harem. Cue panic as she tries to fix Shen Jiu's wrongs and eventually forges a strange, beneficial (coughlovingcough) relationship with the poor girl.
By this point, Binghe is already pregnant. She caught the eye of the Emperor quickly, nature took its course, blah blah blah. She's expecting. She's kinda terrified. She's not sure how Empress Shen is going to take this, so she's hiding it at the moment.
Little does she know, Shen Yuan is very aware.
In the original plot, Shen Jiu had many, many miscarriages. It's a whole thing, and at any point in the day, Shen Yuan gets to delightfully hear someone jab at that like chickens peck at weakness. She doesn't much care. It kinda bothers her, but she decided fairly shortly after transmigrating in that 1) she'll NOT be trying to fix that, thank you very much, and 2) She's just going to adopt Binghe's Baby as her own, because that's a think an Empress can do apparently. So, with Binghe as the birth mother and Shen Yuan as the Legal Mother, this baby is set! Who doesn't want two moms?!
Binghe hears this, has a moment where she tries and fails to contain her feelings, and vows to co-parent this baby with her secret beloved SO HARD!
The rest of the story is them against the rest of the Harem, fending off schemes, poisons, and harassment for each other- and then, after a harrowing moment where the Emperor tries to make more children with one of them (coughshenyuancough) Binghe tearfully admits to her feelings. Cue scheming of their own as they try to figure out how to make Shen Yuan Empress Regent- only to realize the best path for it is if their shared child was to become heir.
Basically, Lesbingqiu: court intrigue/murder wives edition + childrearing. MAY THIS HAUNT YOU!!