OroSasu is the term used to refer to the romantic relationship between Orochimaru and Sasuke Uchiha, in which Orochimaru plays the dominant role and Sasuke the submissive role. The term for the couple where the roles are reversed is SasuOro.
Chūnin Exam ArcEdit
During the second test of the Chūnin Exam in the Forest of Death, Orochimaru disguised as Shiore and separates Naruto from Team 7 by using his snake summoning. The disguised Orochimaru subjected Sasuke to his killing intent with the youth unable to fight due to the fear instilled into him.
However, the fear subsided with Naruto's timely appearance and urging Sasuke not to surrender to the stronger ninja before Orochimaru interferes with the Naruto's jinchūriki seal while knocking him out for the duration of the fight. After being subjected to Sasuke's Dragon Fire Technique as it partially burned off his disguise, Orochimaru expresses pride in Sasuke's abilities then he implants his cursed seal on Sasuke's neck as a reward and taking his leave. Orochimaru have sends Team Dosu to test Sasuke and having Kabuto accompany Team 7 to witness Sasuke use the curse seal's power.
During the preliminaries, Orochimaru disguised himself as the Otogakure jōnin to watch Sasuke's performance against Yoroi Akadō and seeing him suppress the Cursed Seal with sheer will. Orochimaru then confront Kakashi after he seals away the mark on Sasuke. Orochimaru noted to Kakashi that before leaving that Sasuke will eventually come to him seeking power.
In the final round matches, Orochimaru was impressed with Sasuke improvement.
Invasion of Konoha ArcEdit
When the invasion of Konoha started, in the fight between Orochimaru and the Third Hokage, it is revealed that Orochimaru wanted Sasuke's body.
Sasuke Retrieval ArcEdit
Seeing his body condition is worst, Orochimaru sent his Sound Four to retrieve and bring Sasuke to him even though he had hoped to wait for Sasuke to grow older. Orochimaru held out as long as he could, anticipating Sasuke's arrival, but the pain in his arms became too unbearable so he is given no choice but to take the body of Gen'yūmaru. After bandaged up within his new host, Orochimaru waited for Sasuke with Kabuto by his side. During the fight between Sasuke and Naruto is over, Sasuke made his way to Orochimaru. Once Sasuke arrived at Orochimaru's hideout, Orochimaru decided to start training Sasuke, hoping to shape him into the ideal host. Orochimaru was highly impressed and excited by the chakra that Sasuke revealed in response to Kabuto's threat for not giving Orochimaru his respect.
Sasuke and Sai ArcEdit
Two and a half years later, Yamato lead Team Kakashi, hoping to find Sasuke after they learned of an opportunity from a dying Sasori that he was meeting with his spy, Kabuto. When Team Kakashi confront with Orochimaru and Kabuto, Orochimaru was interested to see Naruto and telling him that if he has become as strong as "his Sasuke".
When Sasuke decides to finish off his former teammates, Orochimaru stopped him and noting to him that they might kill another Akatsuki member which would make his revenge easier.
Itachi Pursuit ArcEdit
Sometime later, Orochimaru tests Sasuke's abilities by having him battle with hundreds of Otogakure ninja with no compassion or mercy. Sasuke completes this task without taking a scratch and without killing anyone of them. When inquired about the latter part of the scenario, Sasuke remarks that he only person he wants to kill is his brother, Itachi and leaves to his training room.
On the verge of being rejected by his current body, Orochimaru contemplated how best to take Sasuke's body. In the anime, Orichimaru and Kabuto recapped all the events that led to Sasuke defecting and how much he had improved since then. Before Orochimaru could formulate his plan, Sasuke who deems Orochimaru too weak to be worthy of having his body or the Sharingan, attacks him and tries to kill him with Chidori Sharp Spear but only succeeds in piercing his arm. Sasuke berated Orochimaru for meddling with people's lives for experiments and how Sasuke is disgusted with Orochimaru, who proceeded to reveal his true body, a large white snake made of a multitude of smaller snakes to initiate the body-switch process.
However, Sasuke cuts up Orochimaru's large snake body, only to realise that the vaporising blood is turning into a poison and Orochimaru successfully starts the body-switch process. Sasuke then was able to reverse the process using his Sharingan and gains access to all of Orochimaru's abilities.
During the battle between the Uchiha brothers, when Sasuke ran out of chakra, Orochimaru gained control and reappeared through his Eight Branches Technique. Orochimaru thanked Itachi for pushing Sasuke so far, setting him free, allowing him to have the chance to take control Sasuke's body but was immediately stabbed by Itachi's Susanoo using the Totsuka Sword.
Fourth Shinobi World War: Climax Edit
After Itachi removed to the afterlife, Sasuke started to question what a village was, and what shinobi truly were. While still in thought, Suigetsu and Jūgo found Sasuke and they give him the scroll they had found at Orochimaru's hideout. From what Sasuke reads in the scroll, he declared that he will find the human who knows everything, even if it means reviving Orochimaru. To this end, he used Anko's Cursed Seal along with a piece of Kabuto's altered flesh to revive Orochimaru. After Sasuke succeeds in reviving Orochimaru, Orochimaru explains that he is not interested in Tobi's war but still desires to take Sasuke's body but says he lacks the power to do so. Noting the change in his former student, Orochimaru decided to take Sasuke to one who has the answers he wants.
Orochimaru lead them to the Uzumaki Clan Mask Storage Temple which had fallen into ruin on the outskirts of the village to pick up a mask from the ruins and then takes the group to the underground hall in the Naka Shrine where he unsealed the hidden meeting hall below the temple. Once there, Orochimaru proceeded to don the mask which invoked the Shinigami to possess his body using the spore clones that had been attached to Sasuke as sacrifices to reincarnate the ones who knew everything: the previous four Hokage.
After hearing Sasuke's decision to protect the village, Orochimaru announces that he will also help in the war effort against Madara. When Hiruzen asks him why he changed his mind after all these years, Orochimaru explains that he made an error in judgement from watching Kabuto act in his stead and is now interested to see the result of Sasuke's "different path" of not letting those who sacrificed themselves for the village go to waste.
In the battlefield, when Jūgo transfer some of his natural energy into the Uchiha, who immediately channelled it into his complete Susanoo, Orochimaru watched on, greatly impressed at how far Sasuke has come and notes that he still had much room to grow.
Birth of the Ten-Tails' Jinchūriki Edit
Orochimaru teamed up with his former subordinates to effectively subdue their attacker in order to make a break for Sasuke's location. As they raced towards where Karin last senses Sasuke, Orochimaru noticed that the young woman was expending herself. Contemplating the situation, he wondered solemnly if this was really the end for Sasuke.
Kaguya Ōtsutsuki Strikes Edit
Ultimately, Orochimaru and the rest of the world are freed from the genjutsu by Naruto and Sasuke after they ended the war.
Sasuke Shinden: Book of SunriseEdit
Sasuke meets with Orochimaru to gather information on Fushin and Orochimaru is mused that Sasuke is seeking information for the sake of others rather than himself. When Sasuke explains Orochimaru is the only person with the most knowledge, Orochimaru interprets this as meaning that Sasuke trusts him, though Sasuke downplays this. He agrees to help Sasuke and they travel to the Coliseum to meet with En Oyashiro, during which Sasuke expresses his amazement that Orochimaru is not imprisoned for his crimes. Orochimaru retorts Sasuke is no different but is less likely to resort to evil again.
At the Coliseum, Sasuke is dismayed at Orochimaru for signing him up as a contestant without his permission but decides to go through with the battle anyway to find Oyashiro. When Exploding Humans appear, Sasuke uses his Sharingan to save them, which surprises Orochimaru that Sasuke would save a stranger's life.
Naruto Gaiden: The Seventh Hokage and the Scarlet SpringEdit
Several years after the war, Sasuke and Orochimaru crossed paths once more. Orochimaru was surprised to find Sasuke had come to his hideout on his own will. Sasuke told him about encountering a boy named Shin who possessed the Sharingan and suspected the boy was an experiment of Orochimaru's. Sasuke threatened to harm Orochimaru because Shin tried to kill his daughter, Sarada, and kidnapped his wife, Sakura, and wanted information on Shin's whereabouts. Orochimaru denied any connection to Shin, but under pressure from Sasuke, Orochimaru said Shin was indeed an experiment of his and was delighted to tell Sasuke where Shin was so the Uchiha could kill him as a favor.
- When Orochimaru notice Sasuke has changed after he revives him, Orochimaru decided to help Sasuke.
- After hearing Sasuke's decision to protect the village, Orochimaru announces that he will also help in the war effort against Madara.
- When Hiruzen asks Orochimaru why he changed his mind after all these years, Orochimaru explains that he is interested to see the result of Sasuke's "different path" of not letting those who sacrificed themselves for the village go to waste.
- Orochimaru is shown worried about Sasuke when Karin told him that Sasuke is dead.
Naruto Shippūden the Movie: Bonds Edit
Orochimaru made a small appearance along with Kabuto. Feeling that his time was running out before he had to transfer his soul again, but fearing that the repeated use of his techniques was starting to be too taxing, he ordered Sasuke to retrieve a man named Shinnō, who had developed his own immortality technique. In the end, Sasuke failed to get the man, but did retrieve the scroll containing the technique's information. Orochimaru noticed that Sasuke's demeanour seemed shaken from the mission.
Among the FansEdit
OroSasu is not a popular pairing but it has some numbers of supporters and it still has a few pieces of fanart and some fanfictions. Some fans who ship this couple believe that Orochimaru wanted Sasuke not just for a vessel, but for a lover as well. It is a rival to KabuOro, SasuNaru and OroTsuna.