It starts off with the protagonist, Brigand, as an average high school student, yes the trope to a T. He gets into a car crash, which claims the life of his mother and his sister. (It later turns out that the crash was caused by a Hollow-equivalent. And his mother, a retired shinigami-equivalent, was trying to keep him safe. She failed. And by the way, his mother met his father when she was also hunting a figure of interest: him, because Brigand's grandmother was a hollow-equivalent. I swear, this was coincidental since at the time, Isshin's backstory was not known. It was known that he was a shinigami, and I was copying with a gender-flip there, but Aizen wasn't even close to defeated, yet alone, to the point in the Thousand Year arc where Isshin's backstory was shown, so when I came up with this, it was entirely coincidental.)
From that point, he recovers, only to discover that his latent talent was being awakened. Enter, two figures of interest: Rukia and Renji standins. In MY story, the shinigami-equivalents are divided into two sides, which have even warred in the past: white and black. Since then, a neutral gray squad has formed, and it takes from both black and white sides for missions to earth. They are from rival sides, and have some degree of animosity to one another.
Now, the girl of the two is a combat specialist, and was born into the afterlife.
The guy of the two is more of a magic specialist, and he was once human: he died in America's Civil War, and was sent to the afterlife back then.
They basically are arguing over who gets priority on treating Brigand.
This whole time, Brigand is confused. He knew both of them as two of his newer friends in school. Eventually, without them having done anything, he gains a gray shinigami-equivalent uniform, effectively signifying his powers have begun developing on their own, yet unusually, his body is still alive, just with him having an out-of-body experience.
Exposition happens, training happens, fights against hollow-equivalents happen, and then, a new girl shows up. This new girl turns out to be one of the hollow-equivalents, sent to recruit Brigand to their side. See, the hollow-equivalents in my story come in a few forms:
Animalistic ones are exactly that.
Evolved ones came from animalistic ones.
There's a third evolution, which is tied for other forms:
It is possible for a human consumed by one to themselves become one, in one of two ways--losing their memories but retaining their personality, or losing their personality but retaining their memories. This is a rare occurrence, but it does happen.
And also possible is for a shinigami-equivalent to become one. (I made this before Fake-Karakura started, by the way.) In fact, their current structured leadership is because of a shinigami-equivalent having formed an army of them. (The difference is, instead of this King being an Aizen-like villain, he's actually not a bad guy.)
There's more nuances to it than that, but basically: this new girl was once a human friend of his, who was consumed, yet reformed with her personality in-tact. What makes her unusual, though, is that after coming into contact with Brigand, she begins to slowly regain her memories, becoming closer and closer to her human self, to the point where when she drops the illusion on her appearance (she's a master of illusion), Brigand recognizes her.
The story gets really complex really quickly, but a few other nods that I can say include the visored equivalents, which form when a shinigami-equivalent has had a traumatic, life-threatening encounter with a hollow-equivalent that left an imprint.
See, in this story, the shinigami-equivalent represent "action through thought": intuition. The hollow-equivalent represent "action through feeling": instinct. These instincts, often twisted and brutal, are why the hollow-equivalents are, well...generally the "bad guys", so to speak. And this instinct can infect the shinigami-equivalent, turning them into a visored-equivalent.
This visored-equivalent, if left untamed, can create a terrifying berserker: insanely strong, fast, and reacting at immense speeds, yet the true fear factor is in the following bit: the person normally in control isn't in control at all. It's like a possession, and the demonic power in control has the ability to fight logically, just with an intense bloodlust.
They can be tamed, but the method of taming varies. In a worst-case scenario, the shinigami-equivalent has their instincts literally ripped out of them: they'll still be able to fight, but they're never quite the same, lacking the "battle sense" inherent to all life. In most cases, the shinigami-equivalent tames the beast, learning to control it like a dog, almost, in that they can call on its power to enhance their own in combat, but maintain control.
Brigand ends up having a different resolution after his manifests. (Because he was attacked by a hollow-equivalent when he was young, and is part-hollow-equivalent by heritage.) Instead of dominating, he agrees to equal control: he can now constantly hear the voice of this extra-presence, but maintains control and the extra presence cannot forcefully take control anymore. However, if Brigand lets it take control, it can then go on the offensive.
Basically, you'd think this duality is akin to Hollow!Ichigo and Old Man Zangetsu, but it's not: this is more akin to how conversations between me and the two guys I have residing within me would manifest, only with a supernatural touch to enhance it, with the entity I call David being the effective manifestation of my instincts, and the entity I currently call Brian being the effective manifestation of my thoughts, just with them using different names in-story.
While we're on the subject: yes, there are zanpaktou-equivalents. They represent the soul of the individual, in essence. They ultimately manifest in five stages: Stage 1 is the creation of the weapon. Most take the form of either a longsword or a katana, though they can take any form. Most weapons are without power in this form, though some have powers even when unreleased.
Stage 2, equivalent to shikai, is when the shinigami-equivalent or hollow-equivalent calls out the name of their weapon, with a simple release phrase. It takes a few years of training to obtain.
Stage 3, equivalent to bankai, is when they perform a LONG incantation unique to them, which basically reflects the nature of their power. They then say the name of the stage, and then the name of their weapon in this stage. This is a process which takes them about a minute or two to complete: it's flashy and uses a lot of power. Most do not have a stage 3. It takes years upon years of training, and only the most skilled have one. It is usually considered the pinnacle of power.
Stage 4, my own invention, has them actually perform the same thing as stage 2: a short release phrase (different from the stage 2 one), then the modified name for their weapon if existing. In this form, their guide, their soul so to speak, the manifestation of their weapon, actually manifests in the physical world. This has an immediate obvious advantage: it doubles the number of combatants, as both halves can fight equally. They each have separate, but linked, abilities in this form. Most think this stage a legend, as all who are capable of using this form rarely have the need to.
Stage 5 has them re-merge, combined into a single entity, fully unified. It has only been achieved once, 2,000 years ago, and it has terrible consequences, namely, that this combined form is so powerful that it cannot be controlled. It is not even recorded in history books. (Yes, I created this before the Deicide arc, thankyouverymuch, this was part of my story from the get-go, during which time they were still, at the LATEST, in Hueco Mundo, so this is MINE.)
These are massive oversimplifications. But it can give you a little bit of an idea where the inspiration starts, but also where it stops: this is my story now.