Edit: apparently, in 2020's #askmerlin Q&A with Capps and Murphy, the authors stated that Morgana is younger. What to make of this? Usually, in fandoms, the word of the author/s isn't canon (only what is shown on screen/written in book is canon). Also, still doesn't make sense (see below). With that said, I feel is even more necessary a "parentage" section about the debate of the topic below at both Morgana's and Arthur's pages.
Hiya, long time no see.
I know this is a very old question (and I'm sure there was more than one discussion about this very topic in the old forums), but I feel its time to erase that line in Morgana's page where is says that Morgana is the Arthur's younger sister (and, accordingly, the same mention at Arthur's page). I didn't even remember it, could it be it was changed in 2020? Or has it been there since ages? I can't believe I didn't raise the question back when I was active here in 2019!
Canon unfortunately never stated anywhere their age and who was older. We got a generic "about the same age of Merlin but looks older" in the script for the pilot/1x01. But, again, even Arthur (labelled "Young Lad") is said to be "the same age" of Merlin, and we know that Arthur is at least 1 year and 9 months older than Merlin.
We only have hints (and you have to really squint) that makes her "being older":
1) If she were the younger, her claim to the throne would be outright hilariously ridiculous. As the oldest child of Uther she could at least argue a bit (she was a bastard, but at least she had the point of being the firstborn).
2) If she were the younger, it meant Uther conceived her when he already was widowed. In the middle of the Great Purge. Still grieving Ygraine. Few months after the very birth of his son that cost the life of his beloved wife, he goes to have an affair with a young (fertile) woman? Not much sense?
3) If she were the younger, her claim/dig that she was able to beat Arthur with the sword cannot be believed. If she were older, it would make sense that she would be able to be on par with him, but a smaller girl (who likely spent her time doing/forced to do "girl thing") to beat an older boy (who basically trains 24/7)... hm, no.
Anyway. I mostly point to the first. I further elaborated on a Tumblr post, if you might be interested.
I feel perhaps the best approach would be to completely remove the "old/young", leaving a generic "paternal half-sister/brother" and add a note in which explain that neither the canon nor the authors ever cleared it so the question is up to debate, and eventually the reason for one and the other thesis. [I know there is a proper coding, I've seen it used plenty of times at Star Trek's Memory Alpha, see the dotted square under the first paragraph, hoping it isn't the "quote" code; else, a specific section where to elaborate/write down the speculations?]
what do you think?
P.S. Per canon, we don't even know if Morgana was Vivien's youngest either. We can just surmise Morgause is older because of the actress being much older than Morgana's: I do remember the old admins, in the forum, reaching the conclusion of Morgause being older almost solely based on the casting of Emilia Fox, which is 9 years older than Katie - the argument raised was something like "the authors picked an actress so older than the rest of the 4 main character, must be for a reason, and which one if not to state that Morgause is older than them all?". That and the fact Morgause knows of Morgana and Morgana doesn't know about Morgause, which could be explained as her being present/remembering when Morgana was born). Anyway. Per canon, we don't even know if Morgana and Morgause were the only children of Vivien. If feels like those lines in the introduction of the three characters are most an interpretation (or a mix of interpretation and legends) than a reflection of the canon material.
Oh dear, Morgause's page needs some fixing now that I notice it. And yes, I recall these were reason for heated debates back in the day (I wasn't on wikia at the time, I just read all the forums entries in 2018. BTW, have the old forums been imported in the new script/overhaul of few months ago? Are those discussion still available?). Anyway.
- In the intro it says "Morgause was the eldest daughter of Vivienne", but in the "early life" section it says "it is currently unknown if she had any other siblings, however this is more on the unlikely side". Which means it cannot be stated with certainty that she was the eldest.
- Always in the "early life" there's this line that makes utter no sense: "Morgause was born into one of the noble houses of Camelot, the house of Gorlois - though the man himself is NOT her father as Morgause and Morgana referred to one another as "sister" once Morgana's true parentage (that of Uther) was known"
What does that even mean? That Morgana was Vivien's daughter was widely known (Morgana certainly knew: she was shocked by the revelation that she wasn't Gorlois's daughter only; Gaius knew as well, and didn't come at a surprise when Vivien's name was raised), and since the M-siblings are related by mother... Canon doesn't tell us whether Gorlois was Morgause's father or not. We know she has a bracelet with the Gorlois sigil and we know she was smuggled out of Camelot. That's all. The rest is fancanon, although based on speculations in an attempt to fix what the canon left unclear.
Long. Windy and ubeta'ed. Sorry.