Hidan

was the partner of Kakuzu, despite having mutual dislike for each other, and was the second newest member of Akatsuki, at the time of his expulsion from his village. Kisame laughingly referred to Hidan and Kakuzu as the "Zombie Brothers."

Background
Hidan hailed from Yugakure. After it deteriorated from a shinobi village to a tourist site, Hidan became infuriated with how things were turning out. He believed that the shinobi that resided there were meant to kill, and thus slaughtered his neighbours before leaving Yugakure, and joining the cult-like faith known as Jashin, a religion that worshipped a deity of the same name. The primary teaching of this faith appears to be outright slaughter, where anything less than utter destruction is considered a sin. The amulet around his neck was a symbol of Jashin, and he used it to pray to his god before battling, requesting a good kill, or (when he was not allowed to) for forgiveness. Eventually, he joined Akatsuki, and was partnered with Kakuzu. Pain stated that his reason for joining Akatsuki was "religion".

Personality
Hidan was one of the most foul-mouthed, disrespectful characters in the series; he frequently cursed and complained at allies and opponents alike. He rarely used honorifics when speaking, and, even then, usually as a form of sarcasm. He was the only member of Akatsuki who did not respect their leader, Pain, and openly declared his willingness to kill him around others. The only respect he ever seemed to give was to his god, and, even then, he was quite willing to use his name as an insult. He openly held his partner, Kakuzu, in contempt for his habit of blasphemy, love of money, and Kakuzu's frequent ridicule of Hidan's religion and battle style. Despite this, whenever Hidan was in the mood to kill, the two worked together flawlessly in battle, and one can infer that he did care somewhat for his partner, from his panicky reaction to almost killing him while possessed by Shikamaru's technique.

Hidan had absolutely no moral restraints regarding the people he killed. He considered slaughter a religious calling, and often took considerable pleasure in making his opponents' deaths as painful as possible. Given the requirements of his voodoo-like curse ritual, he was quite willing to inflict pain and injuries on himself, and openly relished the shared pain between him and the cursed victim. Despite this, he reacted "normally" (that is, he didn't enjoy the pain) to being injured by someone else, or when the opponent didn't share the pain.

Hidan was shown to be a sadomasochist, particularly during his ceremony, taking sincere pleasure in the pain he caused his victims and himself. His behaviour in the anime bordered on insanity; he was frequently heard shrieking loudly while attacking, and laughed maniacally when he was about to kill Asuma Sarutobi. Hidan also appeared to be quite spiteful towards his enemies (and nearly everyone else), even commenting to Shikamaru Nara that "I've been waiting for this" ("this" referring to using his ceremony to kill Shikamaru).

However, his immortality had made him very arrogant (though not quite stupid), and he frequently engaged opponents with no regard for strategy, save to acquire some of their blood. Although ridiculed for his foolishness by Kakuzu and Shikamaru alike, and being obviously inferior in tactical genius to either of them, he was able to analyse the nature and limits of Shikamaru's Shadow Imitation Technique, and conducted battle accordingly (though he retained his arrogant attitude even under these circumstances). Interestingly, he seemed to panic when Shikamaru took control of his body, shouting at Kakuzu to do something in a rather frantic voice. He didn't particularly like it when Kakuzu assisted in his battles, and only called for his help when he decided he needed it. Kakuzu tended to return the favour by coming in "late" and letting Hidan "die" as punishment for his arrogance.

Rescue Gaara arc
He first appeared at the sealing ritual for the One-Tailed Shukaku, and when Nagato decided to use the Shapeshifting Technique, he volunteered, as he stated he was having a hard time finding his Jinchūriki.

Hidan and Kakuzu arc
Hidan and Kakuzu made their first actual appearance after cornering Yugito Nii, the Jinchūriki of the Two-Tailed Monster Cat, in the sewers of Kumogakure. Initially, Hidan offered Yugito the option of surrender, claiming his faith did not allow him to fight an opponent only to leave them half-dead (for the capture of her Tailed Beast). Yugito refused his offer, and transformed herself into the Two-Tails, but the Akatsuki duo still managed to defeat her, and gave her body to Zetsu, before they continued to the Land of Fire.

Upon arrival in the Land of Fire, Hidan begrudgingly joined Kakuzu in attacking a temple, so that they could collect the bounty on the head monk, Chiriku. The monk and his numerous subordinates were defeated and slaughtered, and Hidan repeated his lengthy ritual. Afterward, Hidan reluctantly travelled with Kakuzu to take the monk's body to the nearest bounty station.

Reaching the bounty station, Hidan opted to stay outside, not liking the fact that the station was hidden inside a lavatory that smelled particularly foul. While he waited for Kakuzu to collect the money, Hidan was ambushed by Asuma Sarutobi, Shikamaru Nara, Kotetsu Hagane, and Izumo Kamizuki. Despite being immobilized, and stabbed in the chest by two large kunai, Hidan asked who the shinobi were, much to the Konoha group's surprise.

Kakuzu soon arrived, forcing Hidan's assailants to fall back. Instructing Kakuzu to leave the battle to him, Hidan exchanged blows with Asuma, eventually succeeding in obtaining some blood and initiating his curse, right before Asuma used Fire Release: Ash Pile Burning on him, causing Asuma to suffer from third degree burns. Not realising what Hidan had done, Asuma charged, and fell over in pain when Hidan stabbed himself in the leg. As Hidan prepared to kill Asuma, Shikamaru, realising what was going on, again immobilised Hidan, but had difficulty maintaining his hold. While Hidan was momentarily restrained, Shikamaru analysed everything Hidan had said and done up to that point, eventually figuring out the weakness of Hidan's technique. With that epiphany, Shikamaru managed to force Hidan from the safety of his symbol, temporarily releasing Asuma from Hidan's curse.

Now freed from Hidan's curse, Asuma decapitated Hidan. To the Leaf ninjas' horror, Hidan's severed head loudly cursed and swore at Asuma for doing so, and then at Kakuzu for not stopping them. Kakuzu casually shrugged this off, as he felt it was Hidan's fault for telling him to not interfere. While Asuma and the others stood shocked by Hidan's survival, Kakuzu reattached Hidan's head to his body, again surprising the Konoha ninja. As Kakuzu dealt with Kotetsu and Izumo, Hidan re-entered his symbol, and linked himself once more to Asuma. Hidan swung his scythe at Asuma, only for Asuma to duck and the scythe to bury itself into Hidan's own vital organs. Asuma doubled over with pain, and as Shikamaru rushed to Asuma's aid, Hidan used the opportunity to stab himself through the heart with his pike, which fatally injured Asuma. Asuma coughed up blood, and collapsed, as Hidan smiled enjoyably, with Izumo, Kotetsu and Shikamaru watching in sorrow and horror. Shikamaru loudly swore at Hidan, and charged at him, but was knocked over.

Reinforcements from Konoha arrived as Shikamaru was knocked over. Although Hidan expressed interest in getting to kill them as well, the Akatsuki leader called him and Kakuzu away. Angry, and promising to kill the Konoha ninja later, Hidan left with Kakuzu to a secluded area, where they spent three days sealing the Two-Tails (and, in the manga, another three days sealing the Three-Tailed Giant Turtle).

Once the sealing was over, Hidan and Kakuzu headed for Konoha, eager to continue their battle. Along the way, the two were once again ambushed by Shikamaru, the latter having waited for them, this time accompanied by the other remaining members of Team 10. Although Kakuzu managed to escape from Shikamaru's shadow, Hidan was left under Shikamaru's control, and was forced to fight his partner.

When Kakuzu was apparently killed by Kakashi Hatake, Kakashi prepared to finish Hidan as well, but was quickly repelled by a surprisingly alive Kakuzu. Freed from Shikamaru's shadow, due to its inherent time limit, Hidan charged at Kakashi, while Kakuzu fired blasts of elemental attacks at the duo's opponents. Recognising that the two-man Akatsuki team was too powerful as a pair, and needed to be separated, Shikamaru volunteered to draw the immortal away. Hidan, having been trapped by Shikamaru's technique so many times, was determined not to fall prey to it again, and made sure to avoid the shadows. In doing so, Hidan mocked Shikamaru for fighting in a sneaky and distant manner. While focusing on the shadow attacks, Hidan didn't notice Shikamaru suddenly appearing close enough to stun him with a punch to the face. As a result, he was trapped by Shikamaru's shadow, and was led away by him.

Hidan was led towards an area that was surrounded with wire and exploding tags, which Shikamaru had prepared in advance. However, Hidan had no desire to escape, and he attacked Shikamaru when the shadow jutsu wore off. It appeared as though he had acquired some of Shikamaru's blood. Quickly drawing his symbol and transforming, Hidan seemingly killed Shikamaru. Once Hidan departed, the fallen Leaf ninja jumped up, still alive, and tried to decapitate Hidan from behind, although failing to make a cut deep enough. Surprised that Shikamaru was alive, Hidan learned he had been tricked into consuming Kakuzu's blood, so he, in effect, destroyed one of Kakuzu's hearts.

As Hidan attempted to kill Shikamaru in retaliation, Hidan was again stopped by Shikamaru's shadow. With Hidan restrained, Shikamaru covered Hidan with the surrounding exploding tags, tying Hidan to the spot. With Hidan unable to move, Shikamaru activated a prepared mark to cause the ground beneath Hidan to break away. He then informed Hidan that the land that they were on belonged to his clan, and that they would ensure that Hidan remained bound to it for eternity. Finally, having a chance to avenge Asuma's death, Shikamaru lit a cigarette (in the anime, it was changed to Asuma's lighter) and tossed it at Hidan, causing the exploding tags to detonate. Hidan was literally blown to bits. As Hidan's remains fell into the pit below, his detached head promised to kill Shikamaru in any way possible. Shikamaru caused the pit to collapse, trapping the screaming Hidan beneath the rubble. As Hidan was required to periodically kill to retain his immortality, Hidan is considered deceased.

Immortality
Hidan's primary ability was his inability to die, a result of extensive experimenting with the Jashin religion's various jutsu. To maintain this immortality, he must kill others, though it was unclear how many or how often. His immortality allowed him to survive numerous fatal injuries, and almost any form of dismemberment; he even retained his ability to speak after having his head cut off. However, his head still needed to be connected to his body in order to control it, so Kakuzu reattached it, and other body parts, when needed. Even though he could survive these injuries, he was still susceptible to pain, which he came to find pleasure in at the expense of his opponents. This inability to die was the primary reason for his partnership with Kakuzu. Since Kakuzu couldn't kill him, Kakuzu didn't need to find new partners after his fits of rage. Although the two disliked working together, this advantage made them the ideal team.

Triple-Bladed Scythe and Agility
In battle, Hidan wielded a large crimson triple-bladed scythe, that he used as a multi-purpose attack. He wielded it as a short- and long-range weapon, though Shikamaru speculated it was intended to draw blood, instead of doing damage. He controlled it with a long cable, that was connected to a coil hidden under his robe. He was exceptionally skilled at wielding it, capable of deflecting a swarm of shuriken thrown at close range. Hidan stated that the large size inhibited his attack speed, claiming he was the slowest attacker in Akatsuki. Nevertheless, Hidan was extremely agile, having tremendous acrobatic prowess and dexterity in avoiding attacks.

Jashin Ritual and Curse
Using a weapon, Hidan made every attempt to acquire an opponent's blood, whereupon consuming it he drew the Jashin symbol on the ground. This process somehow "linked" his body with his opponent's. Once this link was established, Hidan took on a Grim Reaper-like appearance, with black skin and white bone-like markings. In this state, he was essentially a living voodoo doll for his opponent; any damage that was done to him was also inflicted on the opponent. Hidan referred to this as his "curse", and he was fond of toying with his victims by inflicting non-fatal injuries with his pike, while taking obvious pleasure in their shared pain. Once he was done toying with the opponent, or if he wanted to kill them quickly, he impaled himself through the heart, killing them and relishing in intense satisfaction.

Despite its effectiveness, the curse had many requirements, and could be a slow technique to employ. The curse could be avoided if the opponent happened to know what to look for, and knew of Hidan's inability to die. The link between Hidan's curse and his opponent could be broken prematurely if Hidan was removed from the symbol; however, Hidan would remain in his transformed state, allowing the curse to be easily re-established by him simply entering the symbol's borders once more.

Creation
In Naruto Hiden: Sha no Sho Character Official Data Book, Kishimoto revealed that Hidan's design, with the skeletal patterns and scythe, were meant to resemble a shinigami, or Grim Reaper, because "Hidan uses curses and things." He also noted that he originally planned for the scythe to have a number of special tricks, but "didn't have time to show them all."

Trivia

 * The first kanji in Hidan's name (飛) stands for hisha, the rook in Shogi.
 * Both Hidan and Kakuzu made their first video game debuts in Naruto Shippūden: Gekitou Ninja Taisen EX 3.
 * Though Hidan was immortal, he would eventually, or has already, died. This is due to the fact that his immortality came from killing others while under his curse, which he is unable to do while he is now dismembered and buried.
 * Hidan's favourite food is spare ribs, and his least favourite are vegetables, or any kind of vegetable cooking.

Quotes

 * "Now! Let's savour the utmost of suffering together!"
 * "You're already under my curse."
 * "As the other dies, their agony radiates through my body, and living through it is pure ecstasy!"
 * "Hey, Kakuzu, what do you mean 'unlike my partner?!"