Cale is the Smart Guy of the adventurer group. He acts as the negotiator and he's the one who mostly organizes their money. This is because he is still a Henituse, an extremely wealthy family and the money they earned didn't just come from nowhere. Business management and negotiations are extremely fundamental in nobility education, even at an early age. Cale also looks up each nation's laws since he and the others keep getting involved in so much bullshit that it's pretty much inevitable for them to get in trouble with the law again.
(Also because Lumine actually has little experience with money and item management despite being a traveler for who knows how long. This is because no matter how much money they earn in one world, they become useless once they jump into the next world that had its own unique currency. Also, Aether is the smarter twin while Lumine is the combat ready twin, so she usually lets her twin handle managing their supplies since she'll just mess it up. The twins also don't buy any weapons since they can just magically create their own.)
Cale is a Polearm user. His role is a Sub-DPS (sorry, I'm still not use to gaming terms). Most of his skills are buffs, debuffs and defense but most of his bursts are offensive attacks. But this is only for gameplay, since the genshin characters are a lot more creative with their abilities in story cutscenes (and the manga).
Cale is friends with most of the Archons and views most of the gods of Teyvat to be no different than people, as they have their own lives and feelings, which is why he is willing to give them the benefit of doubt when it came to the Fall of Khaenri'ah, especially since it was clear that they were NOT happy with the Cataclysm and it still greatly affected them to this day, such as Ei. He dislikes the Cryo Archon at first, understandably due to the Fatui's actions throughout the story. However, once he learns how Celestia destroys civilizations due to the "Heavenly Principles", Cale begins to slightly lean onto the Cryo Archon's side. Because while the Tsaritsa and the Abyss Order share the same goal of rebelling against Celestia, at the very least, the Fatui have no intention of exterminating humanity.
Cale's stance on the Gnosis situation is neutral. This is because he noticed how Venti strangely doesn't seem all that bothered over having his Gnosis taken away and how Zhongli and Ei both willing gave away their own Gnoses. After learning of the Cataclysm, Cale believes that it's because that they might actually support the Tsaritsa's goal.
His neutral view also extends to the Tsaritsa herself. He views her as someone who is probably not evil, but someone who is willing to go to the extreme for what she believes is right. Cale also believes that the Tsaritsa may view her entire goal as an "end that justifies the means", which he finds pretty understandable considering that she planning to take down Celestia.
(His neutral stance is also because Cale is a bit more morally dubious than Lumine. He is someone who will allow a Clopeh-esque torture for the worst scums, something that even the Traveler might hesitate to do.)
Cale is scared of Alice. Despite the... strange content of the Teyvat Travel Guide, Cale still can't help but read it, as he feels both excited yet scared. By extension, he is also scared of Klee, but like the rest of the knights, he adores her.
While Cale is capable of controlling multiple elements, the purification power is Lumine's own unique ability. However, he still has very high resistance to corrupt forces like Lumine.
As for why Menogias is alive, in this AU, he survived his battle against Bonanus. In order to prevent mortals from getting affected by his overwhelming karma, Menogias wandered into an abandoned Dunyu Ruins but his lack of a clear mind made him accidentally fall through the Abyss. (Basically, what happened to Childe)
Menogias was captured and then experimented on by Abyss Mages who hold a grudge against higher beings and eventually transformed into a Geo Abyss Lector and became a puppet of the Abyss Order. As time passed, he lost most of his memories due to an overwhelming amount of karma and Abyssal power within him. However, he still barely remembers Rex Lapis and one of the yakshas, Alatus, and would utter their names at times, much to the great annoyance of the Abyss Mages.
(In this AU, the origins of the Abyss Order didn't just start with Khaenri'ah. There have been other ancient civilizations that have been destroyed and cursed by Celestia, since Hilichurls have been around before the Cataclysm, who's to say that Abyss Mages aren't just as old? It wasn't until the Fall of Khaenri'ah that their population increased and they formally created the Abyss Order.)
Since Menogias is an unwilling servant of the Abyss Order, he is not held in the same rank as other Abyss Heralds and Lectors. Despite the loss of his memories, Menogias would still act up against the Abyss Order sometimes, which leads to torture punishments. Due to the difficulty in controlling him, he was never given any missions and was left in the Abyss Domain in Dunyu Ruins with the Abyss Mages treating him like a vicious guard dog. He never met the Prince of the Abyss Order since he remained in Dunyu Ruins the entire time.
While taking on a commission and fighting a Ruin Guard, Cale accidentally fell through the same path (with Lumine and Paimon going after him) that lead Menogias to the Abyss Domain. Cale is separated with the girls. While venturing the maze-like Domain, he encounters a Geo Lector Menogias, who is being tortured for disobedience by the Abyss Mages. The Abyss Mages left without noticing Cale, and the latter cautiously approaches Menogias, who makes no attempt to kill the intruder. Cale is surprised to hear the Geo Lector utter Rex Lapis' name and becomes shocked when the Geo Lector, without any hostility, asks the intruder if he knew who Rex Lapis and Alatus are.
(Menogias knows that Rex Lapis is the Geo Archon, but does not remember him personally as the Abyss Order constantly curse the Archons. Menogias does not remember that he was an adeptus himself. He also lacks knowledge of Liyue as the Abyss Mages never tell him anything because it might trigger his memories.)
Cale begins to have his suspicion over who the Geo Lector might be. The Geo Lector calls Rex Lapis' name without any animosity and called Xiao by his other name and the latter was not one to mingle with mortals, always in the company of the adepti, however, he can't be sure just yet. Cale strikes a deal with the Geo Lector, he will answer his questions if he shows him the way out of the Domain while helping Cale look for Lumine and Paimon who may have entered the Domain as well (he expected that Lumine may have gone after him after he fell). To his surprise, the Lector agrees.
As they venture the Domain, the two slowly grow close. Cale asks the Lector why he is asking about Rex Lapis and Alatus. The Lector admits of only remembering their names not who they are or what they look like. Cale then tries to coax some memories out of him by vaguely telling him a few things about Liyue without telling him who Rex Lapis and Xiao are. Such as:
"Liyue is the Land of Contracts. It is ruled by Geo."
"Adepti serve the Geo Archon to protect Liyue."
"It was once ravaged by war."
It somewhat works, the Geo Lector was beginning to recall fragments of his memories. He also begins to remember the appearances of his yaksha friends, but still does not know who they are.
A large man with four arms, whose demeanor is gentle despite his size.
A woman with hair and personality as bright as fire.
A younger woman whose blue color is the same as water.
A young man who constantly keeps to himself, but would protect others with his green spear.
Cale froze.
Ever since he arrived in Liyue, he had been reading tons of books, whether it were novels or legends.
What the Lector just described sounded exactly how it was depicted in "Yakshas: The Guardian Adepti".
Cale is now almost certain who might this Lector be, and neither Zhongli nor Xiao are going to be happy when they learn what happened to him.
In one of the last few rooms of the domain, they are found by the Abyss Mages.
This expectedly lead to a battle. Unfortunately for Cale, the Abyss Mages forcefully control the unwilling Lector and the latter attacks him. Cale was outnumbered.
At the end of the battle, the reluctant Lector held Cale by his neck.
Cale was going to die if he doesn't think of something quick. The doors around the room were closed by the Abyss Mages. The Lector was both his best chance for survival and possible cause of death.
So Cale raises his voice despite the tight grip on his neck, yelling at the Geo Lector to snap out of it and tells him everything despite their deal.
Morax is the Prime of Adepti, the Warrior God and the man he once served.
Alatus was a member of the five foremost Yakshas and his old friend.
His name was Menogias, also known as "General Kapisas". He was part of the five Yakshas that served to protect Liyue.
Stunned, the Lector lets go of Cale. Menogias begins to struggle and clutched his head in pain. Unfortunately, the return of his memories was not entirely enough. The dangerous mix of karmic debt and abyssal energy had been flowing within him for at least a millennia.
Menogias' focus shifted back to Cale when the redhead suddenly grabbed his hand.
"Form a contract with me."
In the past, there have been yakshas who became too overwhelmed by karma that they would do anything to gain respite. They would force humans to become bound to them to partially transfer their karma. However, mortals were fragile compared to adepti. No mortal lived long after being afflicted by karma. In the current situation, however, it's worse, with the addition of abyssal energy.
However, vision-bearers were known to have high resistances to corrupt forces. Cale and Lumine even more so, as they had the ability the manipulate multiple elements and are equivalent to having multiple visions. Lumine would be the better candidate for this contract due to her purification ability, but she's not here and Cale very much preferred she doesn't do it anyway.
It's either this or be killed.
Despite Menogias' reluctance to form this contract with a mortal, he quickly agreed before the Abyss took hold of him again.
(I have no idea how to do wordy magic contracts like in anime)
As the words echoed in Cale's mind, he opened his eyes to see Menogias' abyssal form slowly dissipating. In front of him was no longer the Abyss Lector, but rather a man whose long brown hair, robe and face markings possessed bright highlights that held the color of Geo. His golden eyes were wide in disbelief, feeling the most relieved he had ever been in a thousand years.
On the other hand, Cale was barely keeping himself together.
The moment the contract was finished, he could feel it. The overflowing rage, hatred, pain and suffering is more than enough for him to feel so suffocated. It was so much that he barely stopped himself from convulsing and collapsing to the floor from the intense pain. He didn't even know whether it was karma or abyssal energy that he was feeling right now.
In the next moment, Menogias turned around and released an intense surge of energy towards the shocked Abyss Mages. His eyes glowed in anger at these insects who made him suffer extensively for millennia.
They didn't even last a minute against him.
Cale's vision was darkening. The beating that swordsmaster gave him a while ago felt so light now compared to what he is feeling right now. He felt like being beaten, stabbed and shot over and over again with no end. Is this what it was like for the former Lector for millennia? He's pretty sure this is only half of the karma and abyss.
Just as his body collapsed to the floor, the last thing the redhead remembers three individuals running (and flying) towards him.
Wait, was that Lumine and Paimon? Jeez, why did they take so long...
Menogias becomes a member of their group since then, feeling nothing but gratitude towards Cale. Unlike Xiao, he is much more curious and shocked to see present-day Liyue and takes an interest in Liyue's modern fashion. His reaction to Zhongli and the whole Osial incident was priceless.
This takes place before Lantern Rite, and Menogias takes it upon himself to spend more time with Xiao.
The five Yakshas have visions. Menogias' Geo vision was lost during his battle with Bonanus. After Menogias has been freed from the Abyss, he, along with Cale and the others looked for his vision and found it in Lingju Pass.
Since making the contract, Cale has been feeling the constant pain due to the combined corruption of karma and abyssal energy, though not enough to corrupt his sanity and soul due currently having two elements, which is the equivalent to having two visions.
(Cale's contract with Menogias is similar to Fate's Master-Servant contracts. In this case, both are on the receiving end of each other. Half of the combined karma and abyssal energy is shared with Cale while the vision resistance is shared with Menogias.)
With alchemy, Menogias creates a version of Remedium Tertiorum, a medicine meant to temporarily alleviate the pain caused by karma, that is nonlethal to mortals. Its pain-relieving effects are reduced as a result.
(They decided to seek out Albedo for help. While Menogias felt like breaking the law for revealing adepti secrets to a foreigner, Cale's health is more important. With the Chief Alchemist's help, they are able to create a nonlethal Remedium Tertiorum that was even better than the regular lethal version.)
Cale takes the medicine on a daily basis. They also have a new objective in their journey: Cale acquiring more elements. The more elements, the more resistance he gets until he's basically near-immune.
(Lumine wanted to contract with Xiao due to her purification ability. But Xiao is very adamant to keep his karmic burden to himself.)
The contract also allows Cale and Menogias to sometime share their memories in their dreams (like Fate). This leads to Menogias to grow even closer to Cale since he had personally seen what Cale had to go through back in his homeworld.
(Cale may or may not have been thinking of utilizing the abyssal energy within him like how Childe does. However, doing so would cause Menogias pain so he decided against it.
[A/N: That is, unless, they get into a desperate situation where even Menogias would agree to utilize it.])
I actually didn't expect to write the Menogias part to be a story but I got carried away, ehe.