Well, it depends on how much of all that was the Nort seed and how much Saix himself which is probably hard to distinguish. I really don't want to take Saix out of the blame, but friendships in this series are not exactly portrayed in a healthy way for those involved. Even though I like Terra I have to say he was pretty much a dick to Aqua through the course of the game - "you're such a girl, hahaha", not being able to be happy for her instead moping about his own darkness when she achieves the dream they both share, being shitty to her when she confronts him and ultimately nearly killing her after being possessed. Aqua is also partly to blame for this, but their relationship is not really looking good and I'm still pretty convinced we'll see some kind of good ending on this part.
I didn't mean to say Isa and Lea have to be friends again right away but it'd find it to be pretty unsatisfying to build up the highs and lows in their relationship just to rub it into our faces how Lea kills Isa off for good. And Axel's perfomance wasn't exactly one of a nice guy by itself in Re:Com, he didn't look very remorseful about killing Vexen and communication was never his strongest skill. He later states he did all that for Saix and their plan (without Saix specifically telling him to), but there's a difference between doing something because you have to and being remorseful about it or doing something because it gives you a benefit without showing many signs of remose. Still, I get your point - maybe all of this is just wishful thinking on my side.
Exactly, but that is the crucial point to determine in what position he falls on the scale.
Friendships can be severed/destroyed for good if there are only coming toxic things out of it
Terra was never deliberately trying to actively harm Aqua though nor did he try to manipulate her into doing shady things by using their friendship as an excuse/source of blackmail.
Terra's main issue is that he wouldn't get his teeth apart and actually talk about his issues and
explain his doings rather than snapping at her which certainly does constitute a flaw in Terra's character, yet it is far from Isa's/Saix's actions in terms of severity.
It is also more than obvious that when Aqua was attacked and nearly killed that those were 100% Xehanort's actions with Terra having no influence about it while with Isa/Saix this isn't clear for any of his actions
except the ones in DDD where he appears almost robotic and acting on Xehanort's will alone.
Terra and Aqua may very well get a "good ending" on their part more because while their friendship got somewhat rocky it never deteriorated to a point where it was so broken they actively went against each other of their own free will, neither from his nor from her side.
Even Sora & Riku in KH 1 deteriorated worse than Terra & Aqua, yet that one was resolved mainly because of Riku himself realizing and admitting that what he had done was wrong by himself, something we have seen or heard none on Isa's part so far.
When overlooking the whole original cast of the KH series the only characters I see so far having fulfilled the
basic conditions for a redemption arc besides Riku are Lea/Axel and Ansem the Wise, although both admittedly could still use some work.
Highs and lows of their relationship? Refresh my memory about the supposed highs as the only thing I remember are some small snippets/cameos from BBS that are vastly outweighed by everything portrayed in both Days and KH 2?
It's also pretty unlikely that we'll get to see Lea "just killing Isa off for good" as he has clearly shown his intent to at least try to save him if he can and it is certainly true that for a time he was fully on board with Saix' and his own plan, yet that changed when Saix began to involve people Axel didn't want to be involved and became increasingly detached and abrasive, that's even stated word for word in the secret reports of Days.
It is certainly possible for Isa to get a redemption arc down the line, I agree with that notion, but from what we've seen so far there is no build up for it and just flipping a switch at the end of KH III and then him and Lea are the best of friends again would be as bad storytelling as the issues of Ienzo/Lea and Kairi/Lea parts so far already are.
It's an issue of doing things too fast and too little in attention to be truly believable.
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In general, I certainly get that many people in fandoms have a knack for wanting a redemption arc for almost every remotely sympathetic bad guy (even if those sympathetic traits are highly subjective in some cases) nowadays, but all too often they tend to get only and directly on the expectation of said bad guy being socially accepted by the good guys (even their direct victims) and deserving unconditional forgiveness and support with this being the
default outcome all the while forgetting or denying that this isn't what a redemption arc actually is about.
The above outcome is the
most positive reward possible but it is not the default nor the core aim of a redemption arc, which actually is for the "bad guy"-character to face the awfulness of what they’ve done, put actual effort into changing and face real consequences for their actions
without being entitled to any acceptance from their victims.
Axel killed Zexion through Replica Riku though, and yet here we are with Ienzo and Lea being all buddy buddy.
That's a sort of different pair of shoes though both in-universe and in meta-terms.
In-universe, not only are Lea/Axel and Ienzo/Zexion not former friends like with Isa, there is also the possibility that as one of the leading scientists in the immoral experiments which may have caused Lea to lose his heart the first time Ienzo/Zexion treats these whole events as a "now we're even" or "I was a scumbag to you so you were one to me"-issue and therefore doesn't feel like bringing it up when it could in return lead to his own shit being addressed.
In meta-terms, it was simply an oversight or shitty writing on Dream Drop Distance's part to not address the history between certain characters.
It may even have been deliberate in order to directly focus on "present problems" and not make the in-between-worlds cutscenes of other characters too long but I can't say I would call this coherent storytelling.
There is no need to repeat the same errors with other cases of characters behaving abusive and shitty towards others being swept under the rug and it is legitimate to point out the idiocy of such an approach even if the writers are likely to repeat it. Especially then I'd say.
I mean, Roxas can share friend groups. He has Hayner, Pence and Olette, which doesn't constitute a trio with him, but he can also be with Lea and Xion, which then can turn into a trio. Lea can also share friends like Roxas does. So I don't see a problem with Isa fitting in with Lea "because of trios".
The whole issue with Roxas/Xion & co. isn't really the big problem anyways precisely because multiple friend groups can be and are a thing.
The main issue will be what is up with Isa even after all traces of (possible) Xehanort influence are purged.
If he remains a petty jealous prick about Lea's other friends I doubt that their friendship will last that much longer nor do I believe that it will ever become as close again as it was before all the shit went down.
Also the fact that Sora's legit apart of two 'trios' with Donald and Goofy as well as Riku and Kairi currently, and Riku has a close bond with Mickey. Roxas is also close with Namine and the two get shipped teased despite Xion possibly coming back, etc. So there is no reason why Axel can't still be friends with Isa 'cuz trio' reasons. :\
Like said, the trio issue isn't the problem, but if after everything that happened this "friendship" is even believable enough to be maintained afterwards.
