Whenever Gwyn is mentioned, I think it's interesting to see how the character react and what SJM says.
"The priestess’s eyes glittered with amusement, as if aware of Nesta’s plan. “Gwyneth Berdara.” Unusual, for these Fae to use family names. Even Rhys didn’t use one, as far as Nesta knew. “But most call me Gwyn.”- pg 113 of SF.
This is the first time Nesta and Gwyn meet. SJM brings attention to the fact that Gwyn has a last name. She uses Nesta to point it out and states that Rhys doesn't use one to her knowledge.
Then we have Nesta bringing up meeting Gwyn to Cassian:
“What happened to the priestesses in Sangravah two years ago?” He went wholly still. It was terrifying. The stillness of a male ready to kill, to defend, to bloody himself. But his voice was terribly calm as he asked, “Why?”
He closed his eyes, as if reeling his rage back into himself. “I heard that Mor had brought one in. Azriel was the one who made it out there first, and he killed any of the Hybern soldiers left, but by that point …” He shuddered. “I don’t know what became of the other survivors. But I’m glad one wound up here. Safe, I mean. With people who understand, and wish to help.” pg 160 SF
Why does Cassian have such a reaction to this? Why is he so enraged? Does he act like this for every rescue. Now in ACOMAF, the Sangravah moment was reduced to like 2-3 lines at best. That will be mentioned later.
Then we have Rhys and Gwyn meeting for the first time:
The casual smile of a male used to people either fleeing in terror or falling to their knees in worship. “Hello, Gwyn,” he said warmly. “Good to see you again.” Gwyn blushed, shaking herself out of her stupor, and bowed low. “My lord.” pg 303 SF.
He called her Gwyn and said it is good to see you again. SJM is implying that they have met before and I doubt he would have said "Hello Gwyn" If this was the first time they have met since Sangravah. Antis love to say that Gwyn was blushing at Rhys so she isn't into Azriel etc. But Rhys is the High lord. It would be like someone meeting a celebrity and being in shock or surprised. In that same chapter Rhys tells Nesta to be nice to Gwyn. He never mentions Emerie while she is standing right there.
Then Azriel and Gwyn meet for the first time since Sangravah:
Gwyn had been distracted today—one eye on the other side of the ring. Cassian could only assume she was watching his brother, who had given Gwyn a small smile of greeting upon arrival. Gwyn hadn’t returned it. Cassian cursed himself for a fool. He should have asked her if she’d be comfortable with Azriel here. Perhaps he should have asked all the priestesses about including another male, but especially Gwyn—whom Azriel had found that day in Sangravah. She’d said nothing about it during the lesson. Only glanced every now and then toward Az, who remained dutifully focused on his charges. Cassian couldn’t read the expression on her face.Pg 406 SF
SJM is using Cassian to point out that there is something going on between the two but we don't know what. Maybe it's the fact that Azriel rescued Gwyn. Maybe its something else. Gwyn was distracted enough for Cassian to notice and she didn't return his smile.
Then in the Blood Rite we get Gwyn's story:
“The first had just unbuckled his belt when Azriel arrived.” Silent, unending tears streamed down Gwyn’s face. “Azriel slaughtered all of them within moments. He didn’t hesitate. But I could barely move, and when I tried to get up … He gave me his cloak and wrapped me in it. Morrigan arrived a few minutes later, and then Rhysand appeared, and it became clear some of the soldiers had gotten away with the piece of the Cauldron, so Azriel headed after them. pg 694 SF
Azriel killed all of them. He didn't save any for questioning. We have examples from MAF of him questioning the Attor. In WAR Rhys killed the Ravens so Azriel couldn't question them and Feyre called it sloppy.(329). Further in SF they spare the Autumn court soldiers for questioning as they are being attacked in the middle. Like this is part of his job. Antis love to say that he left. *Spoilers for CC*/// Hunt showed up, stappled Bryce's wound back together, left her to go hunt down a demon, came back to question her and then ignored her for 2 years until work brought them back together and SJM says they're mates***
For such a "side character", she certainly has a lot of interesting interactions. SJM has Emerie but we don't see Azriel looking at Emerie and giving her a smile. We don't see Rhys telling Nesta to be nice to her even though she is standing right there next to Gwyn. We don't see Cassian going wholly still and enraged over Emerie's wings being clipped. He shows some frustration and curses but its not to the level as he showed when Nesta asked about Sangravah. SJM connected Gwyn and Azriel for a reason. SJM could have picked any of the priestesses in the Library and made up a back story. She made up a backstory with Emerie and Clotho.
In ACOMAF this is what was said about Sangravah:
But Azriel confirmed that they’d raided the memorial in Sangravah three days ago. They’re looking for something—or found it.” Azriel nodded in confirmation, even as Mor cast a surprised look in his direction. Azriel gave her an apologetic shrug back.pg 180
Why did SJM do so much to re-write Sangravah if she could have just made up some random story like Clotho or Emerie. Maybe because the side character is about to get promoted to a main character.