Alkalus was another creation for my friend Mike.
Only, in this campaign, the group was combatting a huge number of planar rifts that had opened up in the Prime Material after a magical accident. So there were areas that were becoming abyssal, or celestial, or whatever, and needed to be closed up.
I found a line saying an artifact was the Codex of the Infinite Planes, a tome that would be able to transport you to any given plane, but had caused much havoc through its existence.
And I swear this all dropped into my head at once.
1) The magical accident that opened all the rifts was, in fact, the attempted creation of the Codex. And in ensuing explosion killed all the people present, save one, a paladin named Alkalus.
2) Alkalus' wife was, in fact, the person trying to make the artifact. And there he woke up, with his wife and all the people he helped, dead, and this blank book, his wife's penultimate work, sitting there. He resolved to complete it, in her memory
3) Alkalus didn't escape without ill effects, though. You see, somewhere Over There in the Prime Material plane, was a world where there was another Alkalus, and another planar accident related to the Codex being created. Three such worlds, in fact.
4) Each one, a level 16-character with five levels in one of the paladin classes, were folded into the same person. LG, CG, CE, and LE alignments, each with his own view, each with his own individual build, each the result of influences in Alkalus' early life. And they all get pressed into the same space, but only one is able to be expressed at a time. Alkalus becomes four men at once.
5) As you might imagine, there's quite a lot of personality conflict happening at first. Alliances for control are constantly being formed and discarded, and the balance of power often shifts, meaning that sometimes, if you're around him, you'll feel a moment when your whole brain makes a sound like a bell being struck or a breaking guitar string, and then you'll experience a brief moment of wondering why Alkalus is wearing different armor before your brain starts saying he's always been wearing that.
6) Eventually, the four Alkaluses (Alkali?) reach one thing they can agree on: They want to complete the Codex. And from then on, there's some conflict, but they tend to tolerate each other and not make such a noise for the one who's currently in control (the one expressed in the world has, basically, three onlookers riding in his head, who can freely and silently communicate with him and one another). After this milestone is reached, they change strategically.
7)LG Alkalus is wearing shining armor, and has a careworn face. He's kind, if a bit stiff. CG Alkalus had a nose that'd been broken and healed a bit crooked, and he was more fun and thought of using caltrops that he'd poured Oil of Invisibility on. LE Alkalus had a harsher face, and carried a Spined Shield and wore Demon Armor. And CE Alkalus had a slightly manic gleam in his eye and about half his scalp was burn scars with no hair growing there.
8) All of the Alkali had level in paladin, but after the Incident, he was pretty much free to violate his alignment as much as he wanted, because the relevant gods got together, discussed things, and agreed that whatever the solution to a perambulatory, reasoning, quadruple-dimensional anomaly is, interfering with it with divine energy is not it.
8) Basically, the party first encountered one of the good Alkaluses, who was a nice guy. And those with the ability tried to scan his alignment, only to get a whanging migraine.
9) He soon helped them close an abyssal rift, and then things got ugly when he broke out a book that absorbed the energy from the rift.
10) Their next encounter resulted in the party's paladin fighting CG Alkalus solo in a Force Cage that was a magic effect from an item of Alkalus. Alkalus held back, stating he didn't want to kill them and really wished they'd just stand aside and let him take care of things, so left the paladin disabled, but alive.
11) Their next several encounters resulted in them sometimes cooperating, sometimes fighting. But they eventually managed to kill LE Alkalus, and got the shock of their life when he blazed with energy and then disappeared, shortly followed by the Codex, which they had just enough time to examine to tell that about a quarter of the book was filled in.
12) I understand the campaign died out soon after, but the background work is:
-when one of the four died, his abilities were distributed out among his remaining 'siblings', meaning that when two were left, he wouldn't be making much sense anymore, but he'd be tough.
-The death also completes a chunk of the Codex, and when all of him are truly dead, the Codex of the Infinite Planes will indeed be complete and in full possession of its power.
-Alkalus, in game terms, had been a cohort to the wizard, his wife, and his alignment and class sprang from her influence. I'm sure that would've have blown the players' minds.
But, hey, he was a cool guy to think up, and, according to Mike, much fun to play against the party.