In this kind of fanfiction, Itachi might use his powerful Sharingan abilities. He could perhaps create illusions to mislead Orochimaru and his minions, then quickly snatch Sasuke away. For example, he could make Orochimaru think that Sasuke is in a completely different location while he secretly approaches and rescues him.
It shows the strong bond between the two brothers. Despite all the complications in their relationship, Itachi still cares deeply for Sasuke and is willing to risk a lot to save him from a great danger like Orochimaru.
Maybe the fanfic could start with the OC being experimented on by Orochimaru. Naruto and Itachi somehow cross paths with the OC. Itachi, seeing the OC's situation, decides to help, which leads to a complex relationship between them all as Naruto tries to understand Itachi's motives and the OC tries to break free from Orochimaru's control.
First, you need to develop your OC well. Give them a unique backstory, personality, and goals. For example, if your OC is a ninja, what are their special abilities? Then, think about how they interact with the existing characters. With Orochimaru, it could be a relationship of fear or mentorship. With Itachi, perhaps respect or a family - like bond. For Naruto, it could be friendship. Also, have a clear plot. Maybe the OC is caught in the middle of a power struggle between Orochimaru and those who oppose him, and Itachi and Naruto are on different sides of this struggle.
In some Orochimaru lemon fanfic, he might be portrayed as having a more seductive or alluring side. However, this is a very unorthodox view compared to his original character in the Naruto series. His intelligence and cunning nature might still be emphasized, but in a more sexually charged context which is not really in line with the official Naruto story.
In Itachi yaoi fanfiction, Itachi is often depicted as a complex and mysterious character. He is usually highly intelligent and powerful, which makes him an alluring figure in romantic or relationship - based stories. His loyalty, whether it be to his family, his village, or his love interest in the yaoi context, is also a common characteristic explored.
In some fanfictions, Orochimaru might develop a sense of loyalty towards Naruto. After being around Naruto for a while, he could see Naruto as someone worthy of his loyalty. This could lead to him being more open to working with the Hidden Leaf and helping Naruto in his various missions. He might even sacrifice his own interests to protect Naruto at times, which is a complete turnaround from his initial character.
Well, in some fanfictions, Orochimaru might use some forbidden jutsu. He could have combined his knowledge of resurrection techniques with some unique chakra sources. Maybe he found a way to reverse the death process by using the power of the snakes he has a connection with. For example, he could have used the regenerative abilities of the snakes' chakra to bring Naruto back to life.
In some fanfics, Naruto might use his new and powerful jutsu that he has mastered over time. Maybe he combines his Sage Mode with the power of the Nine - Tails in a unique way that Orochimaru can't counter. For example, he could use the Nine - Tails' chakra to enhance the range and power of his Sage Mode attacks, and then catch Orochimaru off - guard.
Well, in some versions, Naruto might use his new and improved Rasengan techniques. He could have combined it with his Sage Mode powers to overpower Orochimaru. Maybe he also uses his quick thinking and the element of surprise, since Orochimaru is always so full of his own schemes.