Karin

was a former subordinate of Orochimaru, who was traveling with Sasuke Uchiha. She assisted Orochimaru in his experimentations and was left in charge of one of his bases while he was away. Sasuke sacrificed her in his battle with Danzo by piercing both of them through the heart.

Background
Karin lived in a small village that was burnt to the ground during a war. She was the only survivor, completely unharmed. Orochimaru found her after and asked how she survived, to which she answered that she could tell that huge groups of people were coming. Orochimaru then brought her to Otogakure, where she served as a jailer at one of his bases. Unlike the rest of the team, Karin was genuinely loyal to Orochimaru, going as far as to refuse to release Orochimaru's prisoners and, in the anime only, have them killed for speaking of his death, even after his defeat.

Personality
Karin had a fluctuating personality; she would at times appear tough and in control, to the point of being violent, and at other times would appear highly flirtatious. She annoyed Suigetsu, who she attacked whenever he voiced his general opinion of her.

She, like many girls in Konoha before her, had a huge infatuation with Sasuke Uchiha. Her infatuation, however, was an obsession to the point of fanaticism. For example, when Hebi was resting in a village to take care of the wounded Sasuke after his battle with Deidara, Karin planned to drug Suigetsu and Jūgo to "ravish" Sasuke's unconscious body. She later revealed that she had kept one of Sasuke's sweat-drenched shirts. Karin also implied that a team consisting of just her and Sasuke would be much better than partnering with Jūgo and Suigetsu. Suigetsu indicated that Karin had some history with Sasuke, but this has yet to be elaborated upon in the manga. In the anime, however, it was revealed that her crush on Sasuke began when she aided him in tracking down several prisoners that attempted to escape from Orochimaru. She seemed to rate men on their chakra level, and claimed that Suigetsu's chakra disgusts her. Karin was very displeased when the Fifth Mizukage flirted with Sasuke, and called her an "old hag" for it.

Despite her crush on Sasuke, Karin hadd noticed that his chakra had become darker, and she questioned what happened to him.

Aside from this, Karin showed great intelligence, as she had great control of her chakra, being able to sense and heal others, and even suppress her own presence.

Appearance
Karin had red eyes, a matching hair color, and an unusual hairstyle: her hair was short and unkempt on her right side, while long and combed on her left. She wore brown glasses, a lavender uniform common for Orochimaru's subordinates, short black shorts, and long black thigh high stockings with shoes. Throughout her chest and arms were bite marks that result from using her Heal Bite, and all of which are covered by her uniform.

As she was allied with Hebi Karin began to wear a pouch around her midsection, and later a black cloak. When allied with Akatsuki, Karin wore an Akatsuki cloak with a hood instead of a high collar. After Taka's fight with Killer Bee, Karin briefly put her hair in a ponytail.

Abilities
All of Karin's special abilities seemed to derive from her excellent control of chakra. She could detect others' chakra, transfer her own chakra to heal others, and conceal her own chakra from others. Although she had avoided most battles, she was presumably a capable fighter as she was a former guard to one of Orochimaru's prisons, best evidenced by her effortless take down of a prisoner attempting to escape. She was also strong enough to move all three of her teammates out of the way of an attack at once. She also was able to take a very hard kick from Danzō that launched her from a great height into solid rock without losing consciousness.

Karin's special ability, the Mind's Eye of the Kagura, allowed her to track specific individuals through chakra simply by using her standard concentration pose for molding chakra. For example, she was once able to discern that Jūgo was not among a crowd of prisoners by chakra alone. It also allowed her to pick up chakra from long distances, and notice changes in an individual's chakra. Kakashi Hatake surmised that Karin was a particularly skilled chakra-sensing ninja, as she was not only able to tell that his group is approaching, but could also sense how many of them were present, and that one was a dog. Karin's senses could also tell when a person was lying from the fluctuations in that person's chakra made from dishonest emotions. She could also find out if an enemy was using a clone jutsu and indicate if someone, including herself, was trapped in genjutsu. Karin was praised by the powerful Madara Uchiha as being "helpful" for her abilities and that he made the right choice of bringing her along.

Karin also had the ability to heal others by letting them bite her and suck in her chakra. However, it was dangerous for her to use this ability more than once a day. It should also be noted that she had multiple bite marks on her arms, chest and neck, which were covered up by the long sleeve shirts she wears, suggesting that she has used this power repeatedly.

It is said that she had the ability to completely suppress/hide her chakra from detection. However, doing so will render her unable to use chakra, thus disabling her Mind's Eye of the Kagura technique.

Hunt for Itachi arc
Sasuke recruited her as a member of Hebi. While Sasuke admitted that she might be troublesome sometimes, he also noted that her special abilities made her useful. Once the team was completed, Sasuke sent Hebi out in multiple directions to try and locate Itachi Uchiha. While on the search, Karin passed Sakura Haruno, although the two did not acknowledge each other. After Deidara's suicide explosion, the rest of the team regrouped and took Sasuke to an inn to recover. When Karin went out for supplies, she sensed the Eight Man Squad approaching, and warned the team. It was her plan to use Sasuke's old clothing as a means to distract the squad from catching them. When they finally got back on Itachi's trail, Karin stayed behind with Suigetsu, Jūgo, and Kisame as Sasuke went ahead to battle Itachi.

Hunt for the Eight-Tails arc
Hebi, now renamed Taka, later began working with Akatsuki. They were sent to Kumogakure to capture the Eight-Tailed Giant Ox's jinchūriki. When they found him, Karin stood on the sidelines and watched the others fight Killer Bee. When Sasuke was mortally wounded fighting Killer Bee, Karin immediately rushed to pull the dying Sasuke out of the fight, as Suigetsu and Jūgo kept Killer Bee busy. As she pulled the swords out of Sasuke's body she exposed her right arm, riddled with numerous bite marks. She then told Sasuke to bite her arm, and as he did, her Heal Bite healed his wounds.

As Killer Bee got bored and attempted to leave, Karin used her Mind's Eye of the Kagura to locate him. Killer Bee then used his demonic chakra to charge at her, Jūgo, and Suigetsu, but Jūgo rocketed them away to safety. After Sasuke was yet again critically wounded by Killer Bee, Karin insisted on reviving Sasuke again. She was stopped by Jūgo, who claimed she didn't have enough chakra to save Sasuke again, so Karin watches as Jugo transfers his flesh to Sasuke to heal him. When Killer Bee fully transformed into the Eight-Tails, Sasuke used Amaterasu to quell it. Karin quickly moved all of her teammates out of the way of one of Killer Bee's tentacles, but this resulted in her being hit by one, and some of the black flames spread to Karin's cloak. Sasuke used his Mangekyō Sharingan to put them out. Karin was carried to safety by Jūgo.

While the team was recovering, Karin briefly put her hair in a ponytail. She noticed that something was wrong with Sasuke, but as he brushed it off, she detected an enemy outside their base, which Sasuke and Jūgo went to investigate.

Five Kage Summit arc
After Taka recovers, they move out for Konoha. Along the way they are stopped by Madara Uchiha, who convinces Sasuke to go after Danzō at the five Kage meeting. Upon their arrival in the Land of Iron, they decide to wait until the meeting is over before they attack. Zetsu soon reveals their presence and the Kage mobilize against Taka. When the battle gets under way Karin notices that Sasuke's chakra is now darker than his cursed seal level two chakra.

When the Fourth Raikage arrives, he instructs Shī to locate and eliminate Karin, Taka's sensory ninja. Karin hides her chakra to avoid detection, and once Shī is defeated by Sasuke she again begins looking for Danzō's location. By the time Sasuke is able to elude the Raikage, Karin has found Danzō. She informs Sasuke that Jūgo and Suigetsu are still alive, but he says to leave them and has her lead him to Danzō. Danzō flees as soon as they arrive, and Sasuke is forced to fight the Fifth Mizukage and the Third Tsuchikage before he can follow, with Karin calling the Mizukage an "old hag" for flirting with Sasuke. During the brief confrontation Karin grows concerned with Sasuke's deteriorating chakra levels. When his chakra signature disappears, she breaks into tears, believing him to be dead, with the Tsuchikage turning his sights on her.

Madara soon appears with Sasuke in tow, who sends him to a different realm. He sends Karin with him, telling her to heal his wounds. Later, after Madara confronts Danzō and his men, the former retrieves Sasuke and Karin from the dimension. Madara tells Karin to get back as Sasuke engages Danzō. While Sasuke appears to have a major advantage in the battle, Danzō continues to emerge unharmed after each seemingly fatal assault. Karin notes that her senses indicate whatever Danzō is doing, it is not a clone technique or genjutsu. She also is very observant whenever Danzō takes what seems to be lethal damage, only to emerge unharmed, that one of his many Sharingan embedded on his right arm closes. As Sasuke is paralyzed by Danzōs' binding jutsu, Karin rushes at him only to simply be kicked back, and smashes into the ground. When Sasuke breaks the binding jutsu by releasing his full Susano'o, Karin notices that his chakra is unlike his own. As Danzō uses a Wood Style jutsu to evade Sasuke's Susano'o attack, she discovers the secret to Danzō's abilities. She realizes that the jutsu can only last for a single minute at time, after which one of Danzō's eyes are forced closed. Notifying Sasuke about Danzo's Izanagi, she berates Sasuke briefly for revealing the weakness in Danzo's technique and states that he just has to keep his distance and outlast him.

As Danzō and Sasuke are running low on battle time, they go for one final clash, ending with Sasuke as the victor by tricking Danzō with a Genjutsu to think he still had an arm Sharingan left to use for Izanagi. Karin then went to Sasuke and had him bite her to heal his wounds. Refusing to die, Danzō then took Karin hostage. As Karin called for Sasuke, Sasuke calmly told her to stay still, but to her horror, Sasuke with a deranged smile, stabbed Karin in order to pierce Danzō's heart. Before collapsing, she muttered her horror of what Sasuke did, to which he responded from the moment taken hostage, she became only a burden and obstacle to his revenge. She then collapsed and lay motionless on the ground.

Trivia

 * Karin's name is made up of the kanji for "fragrance" or "perfume" (香) and "phosphorus" (燐).
 * Karin's infatuation for Sasuke leads her to have a number of similarities with Part I Sakura Haruno.
 * Each tend to beat up their other teammate when angry. Sakura would beat up Naruto Uzumaki and Karin would beat up Suigetsu Hōzuki.
 * Both of them are also capable of healing their teammates, as Sakura became a Medical-nin. Though Karin's ability allows her to heal others through letting them bite her, she is not classified as a Medical-nin herself.
 * Both of them are very adept in controlling chakra.
 * Both of them like Sasuke in a fan-girl like manner, although while Sakura's infatuation has matured into a sincere affection, Karin's is more of an obsession.
 * Both of them begin to fear Sasuke for the darkness within his heart, though Sakura has seemingly lost hope, Karin still cares for him.
 * Interestingly enough, despite having saved Sasuke numerous times in the past, she is the first to be betrayed and seemingly killed by Sasuke himself.
 * According to the Third Naruto Databook:
 * Karin's hobby is collecting perfumes.
 * Karin's favorite food is Okonomiyaki, while she dislikes Gyōza.
 * Karin wishes to fight Suigetsu.
 * Karin is a playable character in Naruto Shippūden: Ultimate Ninja Heroes 3. Her ultimate jutsu in Accel 3 is focused on her Mind's Eye of the Kagura technique.
 * Karin is a support character in Naruto Shippūden: Ryujinki, and appears in a new outfit, like most of the characters.

Quotes

 * "Sasuke... Is this all I am to you...?"
 * (To herself)"This guy.. Is cool.."