Spoilers ahead for BBC Merlin S2E08 & S3E05
TLDR: Morgana and Morgause are introduced as half-sisters and implied to share a father, who then is revealed to not be their shared father.
I just rewatched a Morgause/Morgana scene in BBC Merlin and the chemistry is just too good for me not to post this. I've been putting it off in fear of people being weird about it (people in favour of incest please dni!)
This is for the would be Morgana x Morgause shippers who are sad they're apparently sisters not lovers, and a rant against the Merlin writers. Let's be clear: this post is not in favour of incest!!! At all!!! Okay?? Please don't interact with incest readings. I read them as not being sisters a long time before I started thinking they might be queer.
They're not sisters, they weren't written as sisters, they weren't played as sisters.
They're not sisters: The reveal that they're sisters happens in 'The Sins of the Father' S2E08, when Gaius sees that the bracelet Morgause gave Morgana. This was passed down from Morgause's mother, and bears the mark of the House of Gorlois, Morgana's supposed father at the time. He assumes therefore Morgause is Morgana's long-lost half-sister. He doesn't make clear whether they share Morgana's mother, Vivian, or her father, Gorlois, but there is one obvious reason to assume it is their father:
It's Gorlois' seal that Gaius recognises: he specifically states that he recognises Morgause as the baby he smuggled to the High Priestesses because only she 'would have cause' to wear a bracelet with the crest of Gorlois, other than Morgana. It's unlikely that this 'cause' is from a shared mother, because why would she give her daughter a bracelet bearing the crest of a man who isn't her father? Especially when the baby is being sent away to the Isle of the Blessed, for unclear reasons, but presumably because she is illegitimate, and this bracelet will be her only or one of her few keepsakes of her blood family. Why would that tie her back to a man who isn't actually her blood relation?
This is important because in S3E05 it's revealed to Gaius AND Morgana AND Morgause that this is ALL WRONG. Morgana's father is Uther and her mother is Vivian, meaning that she and Morgause aren't actually related at all.
Time to do a Rant:
THEY'RE NOT WRITTEN OR PLAYED AS SISTERS. A lot of the cast and writer commentaries on the episode are in blatant support of Morgana and Morgause having been intended as a lesbian couple. Their chemistry is not accidental, and their dynamic is not that of siblings. I'm all for good sibling relationships in media and this is not one of them. Arthur and Morgana is a dynamic that even with the clearly intended flirting in the first season, is written and played ultimately as a sibling dynamic even in that season: they grew up together, find each other so insufferable they would never admit how ready they are to help each other out, they have a lot of friendly competitiveness, and Morgana is always able to bully him into doing the right thing. With MORGAUSE the relationship is tender, full of yearning gazes, breathy statements that they must have met somewhere before, open desire to care for and make sacrifices for one another, Morgause literally just staring at her sleeping, earnest embraces full of relief that they're finally in each others' arms, caressing one another's faces, magic (which is definitely not a metaphor for anything), and the way that they call each other sister should honestly be illegal.
So why do they keep calling each other sister?
Various theories:
A term of address between High Priestesses/women of the Old Religion.
There are basically no other interactions between High Priestesses or magical women in this show, so it may well be that this was a term of address used in orders like that in the Isle of the Blessed. But again, there are no other interactions so this is purely speculative.
Morgana still thinks of Gorlois as her father.
This is of course not a lesbian reading. Morgana states in series 4, His Father's Son, that she views Gorlois, the man who raised her in her early childhood, as more of a father to her than Uther. So it could be they continue to call one another sister so that Morgana can still feel a part of a family with the father she lost.
The writers didn't notice that they'd written half sisters with a shared father and then got rid of the shared father.
Onto the out of universe explanations - Julian Murphy of course refers to them as 'incestuous lesbians' in the cast commentaries, and they're stated to share a mother on the wiki, so it could be that this is another one of the instances of over-writing something that was implied earlier in the show because there was plausible deniability.
The writers are allergic to queer joy.
Probably the reading most consistent with the rest of the show. We cannot have nice things. I mean, not that they're exactly a healthy relationship but it would be nice to have something canon.