Why Orochimaru's Character Arc In Naruto Makes No Sense
Orochimaru established himself as one of Naruto's most dastardly and evil villains. But his character arc by the end of Shippuden left everyone scratching their heads.
With his massive attack on Konoha, as seen in the Konoha Crush Arc, Orochimaru quickly established himself as one of the biggest character threats in the world of Naruto. And as the series continued on, Orochimaru's numerous sins against Konoha, Sasuke, and even the rest of the Shinobi world racked up. For example, in Shippuden Episode #351, it's revealed that with help from Danzo, Orochimaru kidnapped 60 children for the purpose of experimenting with Hashirarma Senju's DNA. He not only gave the curse seal to Sasuke but, as revealed during Naruto manga Chapter #50, had already tested it on his former pupil Anko.
Throughout the series, Orochimaru used a forbidden jutsu to take over new bodies and was, of course, grooming Sasuke to eventually become his new host before choosing instead to raise him more as his apprentice. During his numerous battles, he has revealed his cursed ability to resurrect and control the dead. And even in the non-canon comedic Rock Lee And His Ninja Pals, he and Kabuto are always trying to somehow take over Konoha. Orochimaru has committed so many crimes it's near-impossible to count. The natural course fans thought they would see for him was ultimate defeat at the hands of either Naruto, Sasuke, or both.
Orochimaru is actually defeated quite a few times
Orochimaru does taste defeat a few times. During the "Itachi Pursuit Arc" in the Shippuden manga, he and Sasuke have what appears to be a final showdown that ends with Sasuke absorbing the villain and keeping him suppressed within with his chakra. Then, several manga chapters later, during Sasuke's climactic battle against his brother Itachi in the "Fated Battle Between Brothers Arc," Orochimaru slips out as Sasuke is low in chakra from his fight. However, Itachi seals Orochimaru away thanks to the Totsuka Sword and his Susanno ability.
It finally looked like the end for Orochimaru. Then things decided to get really weird during the Fourth Great Ninja War. Sasuke ends up resurrecting Orochimaru in manga Chapter #593, and he, in turn, resurrects the four deceased Hokage of Konoha to give the young Uchiha information he seeks. Sasuke then makes the decision to protect Konoha. And as a result, Orochimaru has a change in heart and decides to help his former pupil in his mission. Despite his claims of being uninterested in the war, Orochimaru actually stays true to his word and aids in helping to defeat Madara.
Orochimaru is forgiven and allowed to roam free
By the end of Shippuden, Orochimaru's character arc reaches its questionable conclusion. As mentioned by CBR, due to his help in the Fourth Great Ninja War in resurrecting the four deceased Hokage to aid in battle, everyone seems to forgive the villain for the most part. He is pardoned for his crimes under the condition that he lives under 24-hour surveillance. He continues his experiments but enters into a truce with Konoha and the Five Great Nations. And in Boruto: Naruto Next Generations, his cloned sons, Log and Mitsuki, are introduced to the series. In fact, Mitsuki is currently friends and teammates with Boruto in the series.
Most villains of Orochimaru's stature would have faced a concluding arc that led either to their ultimate demise or plans to survive and formulate an evil plot for another day. Instead, the character who served as a major antagonist for much of the Naruto series is, in the end, left to roam about and experiment despite his numerous crimes.