Many bloody and horrible events happened, but in the end, instead of dying, they were washed away. Suddenly he became a life mentor who untied Sasuke's heart knot. Why on earth is this?
In fact, orochimaru is normal at first, and may even become a new generation of Huo Ying. However, he has been unable to satisfy his talents, which eventually led to the collapse of his mentality.
He tried desperately to prove that he was better than others, thus falling into a vicious and abnormal state of excessive pursuit of strength. Finally, I turned myself into a ghost.
As for why orochimaru was whitewashed, there is a saying that after seeing what happened to Yakushi Kabuto, orochimaru began to reflect on himself. He began to want to turn over a new leaf and start over. He also helped everyone heal in four Ninja Wars and called four generations of Naruto to save Naruto.
We often say, put down the butcher knife and become a Buddha! Orochimaru should be such a representative. Although he did many wrong things, he regretted it at the last minute. He made his due contribution to the ninja world and saved many ninja lives with medical ninjas. Therefore, in order to encourage people to do good, the author should have deliberately left orochimaru's life.
Another point is that orochimaru should have played a very important role in Biography of Boren, so orochimaru's life was preserved, perhaps to lay the foundation for Biography of Boren. After all, Biography of Boren focuses on science, and orochimaru can be regarded as a precedent for creating the ninja world science.