Didyme?? What are your thoughts, please I'm dying to know!
Oh boy, I’m glad you asked, but you probably won’t be once you see the epic I’ve spawned now that you’ve given me the excuse. (But really, thank you so much for asking!)
My thoughts on Didyme can be separated into two thematic chunks. The first has to do with out-of-universe world- and character-building -- namely, I don’t believe Meyer had this specific “Aro murdered his sister and that’s why Marcus is Like That” backstory in mind while writing New Moon (although she probably did in Breaking Dawn). The second is just pure speculative fun, because based on what Meyer tells us in the illustrated guide and a foundation of some meta that I personally agree with, we can draw some...interesting conclusions about Didyme (and Marcus) as a character. (Or at least, we can if you’re a cynical harpy like me. Which I guess is a content warning about negativity incoming, but the negativity is more about Meyer’s logic than Didyme as a character.)
What I’ve ended up doing is answering you with the first chunk, regarding worldbuilding and such, because I’ve truly outdone myself with the Verbosity. (Like, the second chunk has sub-parts now, what the fuck.) But I’ve nearly written it all, and I’ll follow up with part two very quickly. So. LET’S DO THIS.
Didyme, Part 1: What Backstory? (Or, We Should Have Heard About Her in New Moon)
(relevant Kate Beaton comic)
This is a great time to talk about Meyer and her backstories, because @zzinvolterra has already done a chunk of the work for me with this post, with some excellent additions from others, and @panlight has another great post with replies going in a similar vein. The common theme of both is that Meyer most likely came up with the bulk of her characters’ backstories after the fact, otherwise some of it surely would have come up in the books themselves. Didyme, in retrospect, is glaringly absent from the books, particularly New Moon. It makes the timeline of her backstory’s creation, as @zzinvolterra succinctly put it, “a bit sus,” and I said as much here.
Now, I get that not every background detail about a character has to make it into the books -- it would be clunky, it would fuck with the pacing, and when you’re already dealing with a very limited narrative viewpoint like Bella’s, it doesn’t always make sense to include those tidbits unless they directly concern what’s happening to the viewpoint character.
Didyme’s death, though, and its impact on Marcus, are absolutely relevant to the plot of New Moon. The story of one of the three Volturi leaders, one of the most powerful vampires in the world, rendered a mere husk by the loss of his mate -- this sounds like the kind of cautionary tale that many vampires, and especially the Cullens, would know.
Plus, considering Edward supposedly fucks off to Italy to beg for death because he’s lost his ~one true love~ and there’s no point in living anymore, and also considering Victoria is murderous with grief over James and hunting Bella down with single-minded focus on revenge...I just...there are parallels here, you know? Like, these are some significant plot beats that could be reinforced and given special poignancy through the tragedy of Didyme and Marcus. I mean, am I crazy, or was this not a huge missed opportunity?
If Meyer had Didyme’s murder in mind while writing New Moon, she could have had Alice bring it up to Bella on the plane to Italy, in order to illustrate to Bella (and the audience) the profound grief vampires experience when they lose the ones they love. It’s a grief they can’t forget, because they can’t forget anything, and that grief is the dark side of the strength and constancy with which vampires love their mates. As much as the subject is likely verboten in Volterra, I think the loss of one of the leader’s mates is a story that would have survived among some vampires, and it’s conceivable that Carlisle (and therefore his family) would know at least that Marcus had a mate and that she died -- although nothing detailed, because if anyone thinks too hard about this it’s probably obvious that Aro was behind it.
Personally, I think it was a mistake to not mention Didyme’s death and its impact on Marcus at the most relevant point in the series. Hell, if anything, Meyer could have used Bella’s catatonic state of grief after Edward left as proof of the ~profundity~ of their love by comparing Bella’s grief to Marcus’ -- considering the Romeo and Juliet references she dropped like anvils throughout New Moon, that seems like something she’d have pounced on. Because of the omission, I tend to think Meyer came up with it after the fact, which brings me to one more note on the out-of-universe aspect of this: I also believe Meyer only came up with this backstory to further reinforce how eeevil Aro (supposedly) is and how terrible and corrupt the Volturi (supposedly) are. She really scrambles in Breaking Dawn to justify Edward’s conclusion that the Volturi are Bad Hombres and want nothing more than to destroy the Cullens. (He’s actually full of shit, but my view that the protagonists are Meyer’s mouthpieces and that she isn’t subtle at all about what she wants us to believe is a whole other subject.)
And you know, I can accept that Aro murdered Didyme -- but I don’t have to take it at face value. Which means it’s character analysis/headcanon time, so coming soon, like within the hour if I can get myself to shut up -- is Part Two.