Another possible motive is that Orochimaru sees Naruto as a potential powerful ally or tool. Naruto has shown great potential and growth throughout the series. Orochimaru could think that by taking Naruto and molding him in his own way, he could have a powerful weapon at his disposal. He might also want to use Naruto to get back at Konoha in some way, since Naruto is one of Konoha's most important assets.
One possible motive could be the pursuit of power. Orochimaru is known for his vast knowledge of jutsu. Naruto might think that by joining him, he can gain the strength needed to protect his village better or to bring Sasuke back more effectively.
One possible motive could be to change Orochimaru's evil ways. Naruto might think that by changing Orochimaru's gender, he can disrupt Orochimaru's identity and power structure. Since Orochimaru is so used to being male and having a certain way of doing things, being female could throw him off balance.
Well, Orochimaru is a very ambitious and somewhat deranged character. His motives for experimenting on Naruto could be multi - faceted. Firstly, he's always been obsessed with the Sharingan and other powerful kekkei genkai. Naruto, with his own powerful chakra source, might be a step in his research to create something that can rival or even surpass the power of the Sharingan. Secondly, Orochimaru is known for his experiments on humans to enhance their combat abilities. Naruto's natural strength and growth potential could be used to develop new combat - enhancing techniques that Orochimaru could then use for his own purposes, like building a more powerful army or just to satisfy his own scientific curiosity.
A possible plotline could be Orochimaru's redemption. He realizes the error of his ways and joins Naruto in protecting the ninja world. He could use his vast knowledge of jutsu and forbidden arts to help Naruto against new threats.
One possible reason could be in the realm of artistic interpretation in the fanfiction. The author might want to explore a different aesthetic or a unique plot where Naruto has some physical or behavioral traits similar to Orochimaru for shock value or to create a new kind of character dynamic.
They could be related as adversaries with a strange connection. In fanfiction, Orochimaru might be after Naruto not just for the Nine - Tails, but also because Naruto has something that Orochimaru lost long ago. This creates a complex dynamic where they are constantly at odds, but there is also a deeper underlying connection.
One possible motive could be jealousy. If Kiba were to gain more recognition in the village than Naruto in the fanfiction world, Naruto's insecurities could drive him to do something drastic like killing Kiba. But this is a huge departure from his usual self.
The sense of isolation could be a motive. If Naruto never truly felt accepted in Konoha despite his efforts, he might snap. He's always wanted to be recognized, but if that never fully happens, he could turn on the village. For example, if he's constantly passed over for important missions or not given the respect he thinks he deserves as a powerful ninja.
One possible motive could be revenge. Maybe the oc or someone close to the oc has been wronged by Danzo in the past. So, to seek justice, the oc decides to take him down.
He could develop post - traumatic stress disorder (PTSD). Flashbacks of the torture might haunt him during battles or normal daily activities. This would not only affect his performance as a ninja but also his personal relationships. Naruto might become withdrawn as a result of the torture. He might isolate himself from his friends and the village in an attempt to protect them from any potential harm that could come his way because of his association with Orochimaru through the torture. This isolation would further damage his mental state as he thrives on the support and friendship of those around him.