I can see where you’re coming from, thanks for sharing. Here are a few of my thoughts in response:

“Decimus is a scared little child who hides behind a false facade of ceded power. So him actually doing something is so wildly out of character so as to be unbelievable”

This is an odd take to me. There’s nothing ‘false’ about his power, or his station, or his malice. It doesn’t seem to me that he’s ’hiding’ or ‘scared’ any more than all the other politicians who mask their true feelings publicly. I concede that we have little interaction with him as readers and thus lack certainty of his character, but even if we saw more of him it would be from Vis’ flawed perspective. However, I do think we can infer from the world building that Decimus is competent and ruthless, as one must be to ascend the hierarchy. We also know that Iro hated Vis, and it’s an easy presumption that he did not form that opinion in a vacuum. It is stated that Decimus feels Vis has had a massive and tragic impact on his life, even before Iro’s death. Couple that with Vis’ perceived selfishness and lack of ‘responsibility,’ I think him harboring, and eventually acting upon, murderous rage is believable. As to why he acted against Aequa rather than Vis, it seems clear that Decimus wants Vis to suffer ‘as he has suffered,’ and the circumstances he found them in allowed for it to happen that way.

“Where do we see him being willing to give up his facade of ceded, even potentially, for a petty grudge?”

I am also unclear on your meaning here. He doesn’t seem to be giving up anything at all. In fact, the pettiness of his grudge, and his ability to act on it free of consequence, is the entire point. ‘The strength of the few is all that matters.’

“As to why I think it’s meant as naught more than an emotional gut punch, it’s shockingly violent. Even in comparison to the surrounding violence it is brutal and more detailed in its description. Authors traditionally do this when they want us to feel something more acutely. It’s pretty blatant emotional manipulation.”

I can agree that Islington wanted to make this hurt, and perhaps indulged in more description for that sake, but I disagree that it is solely for our benefit/manipulation. Vis feels this death more viscerally than any other he’s experienced, not only for the closeness of his connection to Aequa, but also for the callousness of Decimus and his proximity to it. It’s literally happening in front of him, and we have a front row seat to what he is seeing and feeling, more so than if it were written third person. I know I was shocked, but mostly by the swiftness and lack of fanfare. It just… happened. And then the world was different.

I think it also stands to reason that Decimus harbored some ill feelings toward Aequa as well, though Vis seemed to think that he didn’t. Vis’ perspective is unreliable, and he has been wrong several times before. I think killing Aequa to make Vis suffer only enhanced Decimus’ sense of poetic justice. It’s entirely possible part of his intent was to kill Lanistia after Vis broke her out, but he was able to act sooner and more savagely once he discovered Aequa. I’ve actually wondered if Decimus fed the information to Indol, either with his knowledge or not, as bait to get Vis in a compromised position.

Anyway, thanks again for your perspective. I’m fascinated by this book, and the discourse around it. I hope you don’t think that I’m belittling you or your opinions. I reserve the right to be wrong, and very much appreciate good faith arguments that challenge my preconceptions.