straightforwardly

They're both very self centred people. Each man prefers the qualities in his partner which he also thinks are positive in himself.

Kakuzu likes Hidan's disregard for social bonds and persistent character (even though it annoys him to work around it) and admires his capacity for e-rated graphic violence. He clearly thinks of Hidan as a competent partner — that's why he's able to easily say things like "You're seriously underestimating Hidan," when Shikamaru draws him away from the fight with Kakashi.

I think Kakuzu also likes that Hidan is immortal. When he says that money is the most important thing, compared to bonds with other people or ideology, it's clear that Kakuzu has big problems with trusting the integrity of his interpersonal relationships. Aside from his off-screen history where his important social connections betrayed him (from his perspective), we can also extrapolate this from him being over 90 and still a ninja — most of his interpersonal relationships would have passed. Hidan could last forever, though, he's so poorly socialised that the likelihood of him making high quality relationships with anyone seems extraordinarily low. This is one of the reasons why Kakuzu likes his disregard for social bonds. It is way less stressful for Kakuzu to be attached to someone that cannot be forcibly taken from him, I think.

Even when Kakuzu says, like, we all die sometime, he's comforting himself with the impermanence of their relationship. He doesn't want anyone to take it from him but he also doesn't want to feel trapped by his commitment. What an exhausting man.

I think Hidan's feelings are a lot more romantic and poetic than Kakuzu's. He's a more romantic character. But they're still like... very similar.

Hidan likes that Kakuzu is an immortality trailblazer and looks up to him as an authority. He sees the things about Kakuzu that also exist in himself as beautiful: the deviations from humanity, the violence (even though Kakuzu uses it as a means to an end, and for Hidan violence IS the end), his capricious temper. Hidan has had few role models he really respects — that's why his entire history is very "abandoned his unworthy companions, sought inspiration in god, did some murder." He's poorly connected to other people. He relates strongly to Kakuzu because they're both bad at social connections, they share skills and some interests, and Kakuzu is older and provides a model of what immortality might look like in 69 years.

Hidan also trusts Kakuzu, which is interesting. He trusts him to let him take on fights, he trusts him to pick up pieces of his body and stitch them back together, and he even trusts his situational judgement — for example, when Ino is scouting for them, Kakuzu senses something and turns towards where he thinks she might be. Hidan clearly doesn't sense anything. But he immediately stops and waits for Kakuzu. He assumes, not that Kakuzu is jumping at shadows, but rather that he has spotted something that has escaped Hidan's senses.

Anyway.... hmm, how to wrap this up... oh, I know. Headcanon incoming: Hidan views Kakuzu's serial heart-stealing as his own little ritual. He's a bit patronising about how Kakuzu doesn't recognise it when it's soooo obvious to Hidan. The heart donor dies, and then Kakuzu carries their beating heart with him until it gives out or someone "kills" it, and then he also feels the death he granted them. Clearly a Jashinist ritual by another name.

ETA: I guess they also both think large violent men are hot. Like. Obviously. I don't know if Hidan is into the tentacles for like a deep psychological reason relating to his childhood or whatever... but he's definitely into the tentacles.

Back in August 2024, an anonymous user sent a message to my tumblr blog: "Hidan becomes a Vasto Lorde. Jashin is his zanpakuto ." This was very big brained to me. My thoughts were as follows:

1. This literally just happens to canon Hidan when he finally dies. The pure world rejects him. The shinigami won't take someone who has been so marked by another minor deity. He haunts his own rotting meat until his chain of fate goes through encroachment, and then he becomes a hollow, and he fetches up in Hueco Mundo because he's hungry and that's where all the hollows are.


2. It's really unclear as to whether Jashin, the manifestation of his power and soul, is actually the god Jashin, or if that's a delusion Hidan's corrupted spirit is using to duct tape its identity on. Regardless, Hidan definitely believes Jashin to be the god he worshipped in life, so he is absolutely slavishly devoted to the violent sword spirit that lives inside his head. Together they are unstoppable and ravenous.


3. Hidan's mask is, of course, very similar to the skull-shaped design he has in his Jashinist ritual technique form. His mouth is full of razor sharp teeth, though. There're no flat molars in there anymore. This is a mouth made only for tearing.


4. His hollow hole goes straight through where this third eye would be. He's got a hole in his head and he never covers it up. The howling winds blowing across the empty and endless sands in Hueco Mundo have made him even weirder than he was as a guy.


5. If he were to become an arrancar and get a resurrección/zanpakuto, obviously, the special ability of the Jashin weapon would be to inflict any injuries he takes on his opponents. Hidan's release phrase would be "bleed, Jashin." I am not capable of making puns in Japanese, but I picked one in English, haha. The play on words here is that "bleed," can mean both a) to lose blood yourself, and b) to make someone else lose blood. (E.g., like how you'd use it in, "He'll bleed you dry.") This is a reference to the power of the zanpakuto!

In which Naruto OC Fukuda Fuyumi (the protagonist of my fic Simple Systems) attempts to drunkenly navigate the horrors of Valentine's Day.

Kakashi came around when the fire reached his sleeve. He jolted awake and smacked it into the ground until it stopped smouldering. It stung, but it didn't feel bad enough to even blister.

He thinks they're pretty sad, for all that. Sasori's so-called art is... limited.

He watches him work and he wonders what happens to their consciousness when Sasori binds them in their bodies forever. Does it get trapped, too? Or is consciousness so changeable a thing that he discards it wholesale?

I think you could argue for Hidan's ritual technique being a pure yang chakra release. Much like the Nara shadow manipulation, he uses something belonging to his victim to establish a sympathetic link between them. But whereas the Nara clan use shadows, which make sense as a vehicle for spiritual energy, Hidan's ritual uses blood, which makes a lot more sense as a vehicle for, like, physical energy. Blood has many associations with action and energy and vitality! And then, instead of an invisible binding on people's limbs, the technique opens physical wounds transmitted through that sympathetic link, so I think that's yang stuff as well.

It also makes sense with Hidan's actual skills and character. He might be a spiritual character, in his way, but all his devotions are incredibly physical. Even his meditations appear to involve catastrophic self harm while he does whatever religious contemplating he needs to. And outside of that, he shows next to no ability with non-physical skills like genjutsu or even elemental ninjutsu.

I think any talented yang chakra release specialist could crack that ritual technique wide open and reproduce it if given enough time (most people aren't, obviously) but I also think that the technique itself isn't really the thing that matters? Like, alone, it's not very useful. It's Hidan's execution of it that makes it dangerous. He made it as a vehicle for religious devotion, so he doesn't fuck around with psychological warfare or hostage taking ("kill me and your teammate dies!") or whatever, he just sticks a spear through his ribs and obliterates his own heart.

This technique would only work in very specific circumstances for non-immortals. For example: 1. hostage taking, 2. a suicide technique, 3. if the victim had a very different body type to the user of the technique and therefore things that the user could withstand would kill the victim, or 4. if the user has mad healing skills like Tsunade, Sakura or Kabuto, which grant a certain kind of temporary invulnerability in which they bounce back from lethal damage. Which is basically like time-delimited immortality, really. Are they even non-immortals for the purposes of this list?

So I think Hidan's ritual technique is eminently reverse-engineerable (and Shikamaru could probably tell you exactly how it works, given the whole 'sympathetic link' situation and his own cleverness!) but it's kind of... er, useless.

Except if you're hella religious or functionally immortal. Or both.

"Only sixteen hours left, huh? I'm just saying," said Hidan, hurrying to catch up, "when are you ever going to get the opportunity to have sex as a girl?"