Edmund: My only....sister. Yep, that’s right... [Starts to sweat]
I love Mansfield Park—there's a reason it's so important to my dissertation—and it's not only for the things that seem appropriate enough, but also the ones that kind of break my brain a little.
For me, the Peak WTF has to go to Edmund (surprise), after his sisters have separately run off with two fairly shitty men. He greets Fanny in a burst of emotion:
she found herself pressed to his heart with only these words, just articulate, “My Fanny, my only sister; my only comfort now!” She could say nothing; nor for some minutes could he say more.
I always think ... well, having Edmund refer to Fanny as his sister that late in the book, while simultaneously disowning his actual sisters, is certainly a choice. I don't actually mind it because I don't read MP for Fanny/Edmund, lol, but I find it interestingly bizarre.
(It reminds me distantly of Lord Orville presenting himself as a brother figure to Evelina in Evelina, but iirc that pretty obviously falls apart further from the end and it's clear that he doesn't really see her that way.)
Honestly...that’s perfect!
…Mansfield Park from Edmund’s perspective might look a good deal like Emma, actually.
You’ve got the good sense, the quiet life, the being accustomed to having the best judgement in his little community; then the subsequent falling in and out of temptation and trials, his own judgement proving faulty, other people’s affairs going in unexpected directions; and finally, though unelaborated on, the “oh. OH” moment when Edmund realizes that Fanny has been RIGHT HERE the WHOLE TIME.