ayato I have boba tea

According to Alhaitham's voice line about him, which was available long before Kaveh became playable:

Kaveh gets worked up about everything and is constantly making a fuss. Putting his blood pressure at risk is just what Kaveh does on the daily, whether Alhaitham is involved or not.

Right from the start, we were supposed to understand that Kaveh is a dramatic person. It goes hand-in-hand with his status as an idealist, as someone who pursues his beliefs ardently and believes in beauty and the human spirit, rather than in cold, pragmatic rationality. Just as he's passionate and uncompromising on his ideals, he's passionate when it comes to disagreements too.

From his very first appearance, the point of Kaveh's over-the-top responses to Alhaitham is to establish Kaveh's character as Alhaitham's opposite. Alhaitham is quiet, so of course Kaveh is loud. Alhaitham is discreet, so Kaveh must be conspicuous (charging into the room, arguing publicly). Alhaitham is cool-headed and seemingly unemotional, so Kaveh's first scene will show him as easily worked up, with a quick temper. The whole point of their first scene together was to emphasize these extreme differences in their personalities, so that the "Kaveh is Alhaitham's mirror" plot point would be as obvious to players as it was supposed to be.

Furthermore, we were also given an indication right away that Kaveh and Alhaitham do not fight all the time. In Alhaitham's story quest, the first thing Kaveh does when hearing Alhaitham get home is react happily and ask him to come help with the task he was working on. If they fought all the time and had genuine hatred for each other, would Kaveh have reacted this way to Alhaitham's homecoming at all?

Then, during the follow-up scene to this, Kaveh insists that Alhaitham has to bring him shopping and buy him drinks at the end of the day. If you have a toxic hate-hate relationship where the other person legitimately makes you miserable, would you really be asking to spend a whole day together shopping and going out for drinks, a popular friend activity?

The face of a man who just goaded his "toxic" situationship into taking him on an all-expenses-paid date.

Even the OG message board and NPC interactions for Alhaitham and Kaveh tell us that their relationship isn't one-sided and that Kaveh benefits plenty from being close to Alhaitham. First, we learn that Alhaitham pays Kaveh's tabs regularly, enabling Kaveh to have a lifestyle literally labelled in-game as "like a noble," and then we learn that Alhaitham apologizes to Kaveh by gifting him wine, presumably to make up for times where his comments actually do go too far:

I'll go into the scene where Kaveh is introduced more in a second, but in the meantime, I also strongly push back on the idea that Alhaitham's insults to Kaveh are more hurtful than Kaveh's are to Alhaitham's.

In Alhaitham's story quest, Kaveh flat out asks the Traveler and Paimon if they are paid actors because he doesn't believe that Alhaitham can make other friends. That's pretty damn rude by itself, but coupled with what we learned when Kaveh's character stories were released, what Kaveh said to drive the final spike into their original friendship...

Kaveh was Alhaitham's only friend, and the insult he used to get back at Alhaitham was "I regret ever befriending you." Do you know how devastating it would be to hear that from the only friend you've ever made? Frankly, Kaveh is pretty lucky that Alhaitham is a rational person who can grasp that Kaveh was just lashing out, because while Alhaitham's insult to Kaveh during this argument was born out of concern for Kaveh's well-being ("Your altruism is actually self-harm"), Kaveh's was just a straight-up retaliation meant to cause pain after Alhaitham came too close to the truth.

I think this is far from Kaveh never managing to land an insult, especially since Alhaitham--as far as we are shown--went on to never form another friendship throughout his entire youth.

Anyway, regarding their first scene together, which I'm assuming is the basis for people believing they're toxic... I actually think this scene represents the only time we've ever seen Alhaitham genuinely upset. This scene was meant to highlight the differences between the two characters very deliberately--while also establishing that Alhaitham's behavior around Kaveh is enormously different from his behavior around everyone else.

Alhaitham spends the entire Archon Quest completely unbothered. Even when attacked by Cyno, he gives little more than annoyed noises and cold remarks. He keeps so much distance from the others in the group that all the way to the end, the Traveler isn't 100% convinced they can trust Alhaitham. Although he puts on a very convincing act for Azar, that's the most emotion we players see out of him for the entire Sumeru plot line. He is not presented as an immature person nor depicted as someone who would usually stoop to petty arguments.

Then, suddenly... this.

The moment Kaveh appears on the scene, Alhaitham's maturity just goes straight out the window. Suddenly he's full of snappy comebacks and aggressively getting in someone's face--because he can't be objective and aloof around Kaveh. He can't distance himself from the situation where his roommate is involved.

This scene is actually the one example we have of Alhaitham being upset enough for the mask to come off. We have never seen him this worked up ever again in the entire game.

He deliberately provokes this fight because he was worried for Kaveh--worried enough for the most famously unshakeable man in Sumeru to actually get angry.

First, Alhaitham intentionally stalls, riling Kaveh up by refusing to answer his question about what happened in Sumeru, instead going on a tangent about physical books. Kaveh redirects (with an insult claiming that Alhaitham frequently abuses his position of authority, for good measure), which prompts Alhaitham to remark, oddly:

This is actually the first sign that something is wrong. Alhaitham doesn't usually make incorrect logical leaps, so if he's claiming that Kaveh, who just came back that day, should already know the inside story, what he's actually saying is that he expected Kaveh to be much more in-the-know about the situation than Kaveh actually was. Alhaitham is saying here that Kaveh should have known what was going on in Sumeru, and that idea--Kaveh should have known, should have been there--is the turning point of this entire argument.

Alhaitham continues the conversation by complimenting Kaveh. His tone is sarcastic, causing Kaveh to doubt the meaning, but we players know already from Alhaitham's character stories that Alhaitham actually means this compliment honestly--he sees Kaveh as an intelligent and gifted artist who is his equal in every way. This is a genuine statement cloaked in a sarcastic tone to intentionally escalate the situation.

Then Alhaitham uses Kaveh's exaggerated response as a spring-board to actually snap at Kaveh, specifically stating that Kaveh is unkind to him. This is the only time that we've ever seen Alhaitham express direct and serious displeasure with the way Kaveh treats him.

In many of their early scenes, Kaveh would levy an insult at Alhaitham and Alhaitham would return a snappy one-liner ("If humans aren't humans without their humanity, you'll probably evolve into some other species in another decade" -> "What about you, will you devolve into a fungus?"), or Alhaitham will nitpick at Kaveh's bad habits and Kaveh will clap back with a one-liner of his own ("I hope you are aware of your lack of conversational skills" -> "Oh, so the pot's calling the kettle black, is he?"), but the bickering almost never starts with Alhaitham, and in no other scene does their arguing ever rise above the level of sarcastic and petty complaints.

This is the only time we ever see Alhaitham upset enough to confront Kaveh aggressively, to the extent that he actually stands up to get in Kaveh's space, and then makes a statement that he never, ever makes again:

After this point, Alhaitham will continue to tease and annoy Kaveh by bringing up the rent money, but he will never again suggest seriously that Kaveh should leave. If it wasn't clear yet, it should have been clear from this line: Alhaitham is flat out furious in this scene.

And why? What's got his feathers so ruffled that he completely abandons his aloof demeanor and engages in a public argument?

He didn't know where Kaveh was. The world was basically ending in Sumeru, and Alhaitham couldn't find Kaveh.

In fact, Alhaitham probably even had reason to be worried directly for Kaveh's safety (although he later tries to blow it off): Kaveh was sent out into the desert specifically by the Kshahrewar Sage, who was colluding with Azar, possibly to get Kaveh out of the way. As the Scribe who would be the one approving the paperwork for all the scheming that was going on, Alhaitham would have known that Kaveh had been sent out to desert--a favorite tool for the Akademiya to "disappear" other people in the past.

Actually, if you want to say that any element of Alhaitham and Kaveh's relationship is toxic, you would have better luck with the claim that Alhaitham is kind of a stalker. It's not stalking if the other person wants you there. Being all up in Kaveh's business is basically Alhaitham's actual full-time job. Kaveh's in Port Ormos? Well, what do you know, so is Alhaitham! Kaveh is out on a trip in the desert? Dang, what a coincidence that Alhaitham just so happened to want to explore that exact ruin at that exact moment, out of the entire thousand square mile desert...

Whatever reasoning you want to ascribe to this, Alhaitham goes where Kaveh goes. He dips out mid-conversation the moment Kaveh returns home. He serves as an announcer on an event strictly because it relates to Kaveh. He constantly intervenes when Kaveh is in trouble, appearing conveniently the moment Kaveh needs him for anything.

Remember that, at this point in the story, he literally had no one else. At the start of the Archon Quest, Alhaitham had no family. He had no friends. He only, only had Kaveh. So when the entire city started going mad, a plague that was relatively rare suddenly began raging out of control and killing people, the sages started plotting some kind of insane uprising, Forbidden Knowledge was released on the black market, the arts in Sumeru came under serious attack, important people like Tighnari were targeted, Cyno was sent to oppress him, and public figures in Sumeru started actively disappearing...

For Alhaitham to not know where his one person was?

For Alhaitham to have gone from Sumeru City to Port Ormos to the literal wastes of the desert and still not find Kaveh?

Alhaitham actively glosses over a summary of what happened in Sumeru's Archon Quest because it doesn't matter to him in comparison to what he wants to know, the matter of Kaveh's safety.

He has no issue talking to anyone else about what happened with the Sages, and he's plenty talkative about the events and the Akademiya's status the moment the Traveler comes up right after Kaveh. It's only with Kaveh that he downplays and refuses to share the information about what actually occurred, because he was worried and upset that Kaveh disappeared. Kaveh could have been involved and wasn't. He wasn't there when Sumeru needed him--he wasn't there when Alhaitham needed him.

In a situation where disappeared people were turning up dead in the desert, Kaveh wasn't anywhere to be found at all.

Alhaitham provoked this entire fight and the only point he focuses on, harping on it repeatedly, is: Where were you?

This scene hammers home two messages incredibly well:

Kaveh is the polar opposite of Alhaitham.

Alhaitham cannot emotionally distance himself from Kaveh the same way he's able to be disengaged from everyone else.

This is definitely not the most pleasant of scenes, and starting out with the characters in a bad mood with each other was a very specific choice (one fueled mostly by the need to create plausible deniability so that they could get "my god they were roommates" past the censors, if you ask me), but just because two people have a fight does not make them "toxic."

Both Kaveh and Alhaitham had valid reasons to be worked up in this scene, and considering this is the only scene in which we ever see Alhaitham act so aggressively and with such seemingly genuine anger, it should have been obvious that this was out-of-character for him, highlighting the fact that his relationship with Kaveh is not the same as his dispassionate, cool-tempered reaction to everyone else in the story so far.

Alhaitham got mad and his temper came out, but it turns out that Alhaitham's temper (which Kaveh loves to point out) is connected canonically to his frustrating failures to protect Kaveh--sometimes from Kaveh's own self. Their first fight happened because Alhaitham was too honest and popped off about Kaveh not taking care of himself, and the first fight we get to see from them on-screen is Alhaitham once again genuinely frustrated by Kaveh potentially being in a dangerous situation.

(The humor of this moment is that just like Alhaitham is reluctant to tell Kaveh the truth about what he did in Sumeru, Kaveh conveniently side-steps the reason that he was nowhere to found: He was trapped in a magical bottle fairyland at the time, so Alhaitham couldn't have found him even if he had searched high and low.)

Kaveh, predictably, meets Alhaitham's temper with a full blast of his own over-the-top reactions, including suggesting that he's going to start a rumor that Alhaitham staged a political coup on purpose--something which Kaveh, who knows Alhaitham perfectly well and knows Alhaitham is just flat out too unambitious to ever do, obviously doesn't honestly think. Neither Kaveh's insults nor Alhaitham's hold any particular weight in this conversation, and out of the two of them, Alhaitham actually has far more complimentary things to say about Kaveh than Kaveh ever has to say about him, still to this day.

Personally, I think that seeing Kaveh as the "victim" of Alhaitham's barbs in their early scenes is a misread on Kaveh's character. A massive point of Kaveh's character is that he's literally the architect of his own suffering. He blamed himself for his father's death and his mother's decline, which crippled his ability to form healthy relationships with others in his childhood. His self-sacrificial behavior and--explicitly, in the canon text--his own inability to confront reality led to the collapse of his original friendship with Alhaitham.

He bankrupted himself for the Palace of Alcazarzaray, martyring himself on the altar of his own ideals. He gets into fights with his clients because he isn't good at drawing boundaries, isolates himself from his friends because he feels like a burden (even though they all clearly love him) and then laments feeling lonely, and constantly bickers with Alhaitham even in moments when Alhaitham really hasn't done anything to start a fight, like when Alhaitham brought the Traveler and Paimon home and Kaveh spent half of his first conversation with the Traveler bad-mouthing Alhaitham, who wasn't even in the room to provoke his ire.

While Alhaitham is absolutely not a saint and is a nitpicking champion, the bulk of their bickering comes from Kaveh's tendency to anger easily, his helplessness and lack of control over his financial situation, and from his internalized assumption that Alhaitham is incapable of altruism.

Even realizing that Alhaitham's words in the past came from a place of honest reflection on Kaveh's well-being, at the beginning of their scenes in-game, Kaveh still can't bring himself to let bygones be bygones, still can't accept a freely offered hand, and ultimately ends up taking out a lot of frustration about his personal situation on Alhaitham, the symbolic lightning rod for all of Kaveh's woes. Kaveh isn't comfortable with himself, so he's interpreting every thing Alhaitham says and does in the least charitable way possible--and Alhaitham is, in part, letting him do that (actively encouraging it even), because that's what Kaveh needs. If Kaveh is incensed and railing at Alhaitham for this or that petty disagreement, then he isn't withdrawing into depression and off making rash decisions that will ruin his own life again.

The alternative to Alhaitham taking "snipes" at Kaveh is this:

So I think we can all agree which one is less toxic, lol.

Kaveh also believes that Alhaitham is his mirror--but in a negative way, with Alhaitham being the strawman Kaveh repeatedly builds up to fight against in his quest to justify his idealism, even when that idealism brings him pain. If Kaveh's ideals are just and righteous and good, then Alhaitham--who represents the dead opposite of Kaveh's idealism--must automatically be bad. Alhaitham's selfish, he's egotistical, he'd "let people drown" (said without the self-awareness to note that Alhaitham never let Kaveh drown)... At least when we first started seeing them in game, Kaveh has created an image of Alhaitham that has little to do with the actual reality of their situation.

Kaveh could have had peace from Day 1 in Alhaitham's house if he could keep his own temper in check and stop rising to Alhaitham's bait--but that's not who Kaveh is. He isn't actually a peaceful person by nature. He's kind and generous to a fault; he believes in doing right by others and in putting his heart and soul into every project he brings into the world, but he's also just kind of quarrelsome. Even if he doesn't actually like to argue, he can't help himself because he is passionate about the things he feels and believes. He's impulsive, doing what he feels is right in the moment far more than reasoning rationally about his circumstances (another point of opposition with Alhaitham), and, despite having cripplingly low self-esteem, he's also a proud person, trying overly hard to protect his reputation, so that even just being in Alhaitham's house puts him constantly on edge, fearing that people will find out about his bankruptcy.

Kaveh's tense situation with Alhaitham in their early scenes is, in large part, Kaveh's fault, stemming more from his internal issues and wounded principles than from what is actually going on between himself and Alhaitham in that moment. He's carrying so much emotional baggage into their home that nothing Alhaitham is doing could ever be considered more toxic than the weight Kaveh came into the relationship already bearing--and clearly, as we've seen their character development continue, Alhaitham's methods are working.

Kaveh is much better off now than he used to be.

This isn't to say that Alhaitham is the victim instead, just casually bearing the brunt of Kaveh's personal issues--Alhaitham has issues of his own that he's also working through! Alhaitham is a flawed character whose lack of social skills caused him to experience extreme isolation throughout his youth and into adulthood. Alhaitham claims he prefers this isolation, and yet abandons it instantly the moment he actually manages to form friendships during Sumeru's Archon Quest, now going out of his way to attend social gatherings and even feeling attached enough to Paimon to enroll her in school.

Alhaitham did cause Kaveh pain in the past by being too honest. He had to undergo character development to get to the point where he could understand that "being correct isn't the same as being right." He did have to learn to apologize and to rein in his temper, to "save the bickering for later," because he simply wasn't good at--and still clearly struggles with--communicating his actual feelings about a given situation. We're told this is such a ubiquitous flaw of his that basically everyone who has actually met him thinks Alhaitham is a heartless person, despite Alhaitham generally being laid-back, surprisingly nonjudgmental, and respectful of people even when they come from wildly different backgrounds, like his attempts to get Dehya to join the Akademiya.

To this day, it's obvious that Alhaitham still hasn't managed to make his actual care for Kaveh clear to Kaveh--and he seems mostly content to just wait for Kaveh to figure it out, rather than putting himself out there and (hilarious for the character who knows twenty languages) just using his words. Alhaitham is a little allergic to being forthright, and his relationship with Kaveh moves a glacial pace in part because of that.

So no, their banter didn't sound friendly at first because it wasn't friendly at first. It wasn't supposed to be! They're two flawed people whose personal hang-ups are very difficult for them to overcome, making it extremely hard for them to connect and communicate. They both hurt each other badly in the past, and they're still not over that pain because they've never managed to confront and properly address it. Both them are carrying some intense emotional baggage into their house and struggling to make life together work despite those weights they're carrying. They don't really know how to even be friends because the way they were close before was exactly what fell apart on them in the first place.

But making mistakes in the past, even if those mistakes caused pain, doesn't make a relationship toxic--it just makes it human.

(Okay, just a real world side note here that you can entirely skip if you don't want to hear me rambling... Maybe this is coming from the fact that I'm old, your local fandom mom for real for real, but I sometimes find myself genuinely concerned that younger people seem to really struggle with the concept of conflict. There seems to be this sentiment that relationships should be entirely free of fights, that you shouldn't have to reason with and critically examine your stances on conflicting moral perspectives, that you shouldn't be confronted with criticism--I think this extreme avoidance of conflict is at the heart of a lot of issues we're facing in fandom today, such as fans' inability to handle characters who do bad things or the war over whether shipping reflects people's morality. We operate on black-and-white instead of seeking dialogue and accepting nuance.

Embracing conflict as a core part of life involves recognizing the person facing you on the other side of the conflict, accepting that others' perspectives may differ from your own, making peace with the idea that people may say things you don't want to hear...

Somewhat hilariously, I think that the inclination to view Alhaitham and Kaveh's early relationship as toxic perfectly aligns with the core issue that Alhaitham and Kaveh themselves had--neither one of them could tolerate the discomfort brought on by an opposing ideology, the same way many people nowadays struggle to accept situations that are not perfect from the start, where mistakes are made and truths are sometimes spoken too harshly.