Consumed though I've been by the Jaina Proudmoore/Sylvanas Windrunner AO3 tag, I know this is supposed to be my Star Wars blog, so I'm gonna try to dump all my Sylvaina thoughts into this one post.
By all accounts, those two women have barely interacted in canon, and that ship seems to exist partially to save them from their very male profic writers. As you may have observed, shipping female characters together to that end is already something I quite enjoy.
I've never touched a Warcraft game in my life, but I've been told some pretty ghastly things about how Sylvanas in particular was treated in the profic. Telling a woman she's just as bad as the entitled man-child who violated her in unimaginably horrific ways? Not a good look.
Anyway, I especially love the part of Sylvaina fics where Sylvanas and Jaina realize how much they have in common, and get to bond over shared trauma. Jaina after Theramore having a bunch of other scars from the magic nuke that turned her hair white, and Sylvanas seeing those and immediately being reminded of her scar from Frostmourne? The good shit.
More good shit: Sylvanas thinking she's a hideous, repulsive corpse, and Jaina's just like "Shut up and kiss me."
Dark Ranger shenanigans are always fun, batch of little chaos gremlins that they are.
Jaina Proudmoore is too good for Azeroth.
The Lich King is one of the few things about WoW that I knew of before, because I've been seeing that armor's likeness in the form of a youtuber's minecraft skin for like half my life. Once I started reading Sylvaina fics, I didn't take long to discover that Arthas was a total dick long before he was the Lich King. He's very useful as an antagonist because he's so easy to hate, especially since his bullshit is often part of the reason Jaina and Sylvanas - two victims of his bullshit - get to meet and start to bond.
Anduin is a gay little cinnamon roll.
I don't know if it's like, a fundamental difference between fan cultures of different genres, but I have noticed that in most Sylvaina modern AUs I've read, all the fantasy races still exist - like, Sylvanas is still an elf - which is different from my experiences in Star Wars fandom that almost always has everyone be human in AUs like that.
Sometimes the fic writers try to depict Azeroth's major navies (Kul Tiras tends to be most relevant because Jaina's from there) with reference to our own age of sail, and I guess I have The Sojourn to thank for me knowing what a "first-rate ship of the line" is, because I probably wouldn't have cared enough to look it up myself.
The political marriage trope that's so popular for Sylvaina is something I think I have mixed feelings about. Some of my favorite fics of them are well-executed versions of that, but I'm not always interested in reading thousands of words of them only putting up with each other for peace on Azeroth before they start to realize they actually care about each other.
Jaina and/or Sylvanas getting to personally kill Arthas is always cathartic to read, since they were robbed of that in the game.