The creators once posted sometime after S7 concluded that they had considered giving Karim a redemption arc before deciding that having him die making one last poorly thought-out power grab would be a more satisfying conclusion for his arc. I have no complaints about Karim being irredeemable, but how do you think making him beyond redemption is a better choice for the overall story?
Karim is one of my favourite characters in the show, and going forward into S6/S7 I wasn't entirely sure which way his character arc was going to land. I'd expected him to win in S6 (so that he could free Kim'Dael) and so that he'd have further parallels to Ezran (S4/S5 meta on that here). This was mostly due to me expecting Karim to foil and be a contrast to other characters — Callum, Viren, Ezran, Janai — as his primary narrative role.
For Callum & Ezran, it was as brother-mages (Callum) who'd betray the other (over Runaan) whenever that plot point came around. For Viren, Karim was following his path politically and was usurper. For Janai, ridden with uncertainty and doubt, Karim was impulsive and all too certain.
However, it was evident that the brothers would reconcile (they did), that Viren had cinched a continuing atonement arc (already in s4, then outright in s5 — which, afterwards is when the bulk of the linked meta was written), and that Janai would ultimately reclaim/remain being queen of her people.
So where would that leave Karim?
An important note I think, then, is that TDP has never preached complete pacifism. It has always, routinely, framed violence as a last resort but still a resort, and that figuring out what is worth violence vs what isn't is a crucial, difficult, but occasionally achievable process. Ezran is the most pacifistic character by far, and he still has a huge attempted "people I (would've) murdered" body count after all.
So I'd argue that TDP's stance isn't so much as "people can always change" so much as it is "you have to be real damn sure that a person Won't choose to change before you kill them". And even then, it acknowledges that stopping a person from doing active harm in that moment even unto death/murder (S3 Viren with Rayla; S7 Aaravos with the archdragons) is not an exclusively bad thing, either.
Life is precious. Life is valuable. We take it, but we do not take it lightly.
What then, is 'irredeemable' in TDP? To put it simply, there's not much: you can kill someone, or kill someone's beloved family member, or orchestrate a war, or gaslight/deceive people, or burn people alive, or repeatedly use dark magic or consume your own flesh, or all of the above, and still be considered Redeemable within TDP depending on 1) why you did any of the above regarding the Circumstances and/or 2) if you changed afterwards.
That doesn't mean you're going to get endless passes, not every character can have the same arc for both time, variety, and personality, but most characters (Kasef, Viren, Claudia, even Aaravos) have at least the seed of potential to make better/other choices.
With this in mind, Viren's atonement/redemption arc being almost exclusively about his interpersonal relationships > his global political wrongdoing makes the answer abundantly clear as to what TDP thinks is unforgivable if you don't come back from it: forsaking your loved ones.
This does not mean abandoning them, or even standing / fighting against them. It doesn't even necessarily mean killing or trying to kill them!
It means seeing them as JUST the enemy or JUST a thing. Just an obstacle or barrier in your way, or a tool to use for your own ends.
This is, notably, when ultimately dooms Aaravos in S7. He forgets about his child (Sir Sparklepuff) till it catches him off guard. He does not fathom that Avizandum's love for his mate and child could be stronger than Aaravos' control over him. And it is this forgetfulness, this 'twisting' of love into something else, that Terry lampshades as well: "Maybe this started out as a story of love, but along the way it got twisted. He isn't doing anything for love. He's doing it out of revenge" when it comes to personal love, and Runaan when it comes to other matters: "I remember I fought you. I tried to kill you! How could I?" / "I was a peacemaker, a twisted peacemaker, I suppose [...] but I am not dead. I am alive. I have a family I love."
Much like Kasef is 'punished' narratively for his impulsivity and penchant towards violence, providing a contrast for our young heroes and proof that not every young person will make the same choices they did, Karim is a cautionary sign of what happens if you forsake your loved ones — and you do not recover it.
There's a reason that despite walking Viren's path in so many ways, Karim does not recover the same way Viren did, because Viren re-learned how to see his children as people, not objects. Not heirs or spell parts or assets.
Karim became so concerned with seeing others — his family members, his loved ones — as symbols (things), he lost sight of everything else. He got so swept up in seeing Janai as a queen, and then a false queen who was in his way, that he couldn't see her clearly as his sister anymore, and this eventually extended to everyone / everything else in his life, including himself (viewing himself as a martyr, a true king, a flame to remake the world through).
This is also why the broyals reconciliation is through the lens of "we're brothers and we need each other" and has nothing to do about being king or high mage. Those are their jobs and especially for Ezran are important parts of themselves, but it's still just parts, not the whole. It also helps indicate that Claudia and Soren at the end of 7x09, who clearly do still hold love for each other, are not as broken as Janai (who retained love) and Karim (who did not). None of them ever lost love like the way Karim did. There's a lot throughout arc 2 about how steadily he got there, which may be worth a meta someday, but who knows.
The actual manner of death — Karim swaggering in arrogant and puny as ever, severely overestimating his power and leverage, with consistent focus on his hands (his red glove, holding 'fate' between his fingertips with the sun seed) being little more than a red smear in Aaravos' hand is also some deliciously chewy symbolism and an ultimate slap in the face (deservedly so) to his own ideals of grandeur.
Is there an interesting story to explore of Miyana, or something else, being a catalyst for Karim changing? Sure! But I think Miyana and her children's situation — as well as her potential dynamic with Janai and Amaya — is infinitely more interesting given his absence, as well as allowing Karim to occupy a more unique part of the narrative with his thematic explorations. He's a fantastic character foil and character in his own right, and I think he embodied everything they set out to do like, absurdly exceedingly well.
So short form answer: yes! I'm inclined to agree that it's a more satisfying ending tbh, especially with his writing in 7x03 onwards! I do miss him dearly, though. I miss him every day.
