The abilities might be different too. Since Naruto has his own set of skills like the Rasengan and Sage Mode, his Susanoo could incorporate those elements. For example, his Susanoo's hands could form giant Rasengan - like attacks, or it could have the ability to enter Sage Mode, which would be a huge departure from the regular Uchiha Susanoo's abilities.
Well, in many fanfictions, Naruto might first awaken Susanoo during a really intense battle. Maybe he's pushed to his limits while fighting a super - strong enemy, and his latent Uchiha blood (if that's part of the fanfic's premise) gets activated, leading to the awakening of Susanoo.
Sure. There could be fanfics with this concept. Naruto is known for his own powerful abilities like the Rasengan and Sage Mode. But in the world of fanfiction, writers can bend the rules. Maybe in a story, Naruto gets the Susanoo as a result of a powerful curse or a gift from an ancient being. It would be really cool to see how he would use it in combination with his existing skills.
She could try to appeal to Sasuke's emotions. If she can remind him of their past, of the times they fought together and cared for each other, it might make him release her. Sakura could talk about their shared experiences and how they are on the same side deep down, hoping to break through whatever is making Sasuke hold her captive.
Another way is to have Naruto fuse his chakra with someone who has the ability to use Susanoo, like Sasuke. They could create a combined form that has the best of both their powers. The story could detail their journey of learning to work together and master this new form.
A great fanfiction concept might be that Naruto somehow gains the Sharingan and Susanoo abilities. Maybe through some sort of experimental jutsu gone wrong (but in a good way). He then has to learn to control these new powers while still maintaining his own Sage Mode and Nine - Tails chakra. It would be interesting to see how he combines these different power sources to fight against new and old enemies.
One possible fanfiction could be about Sasuke using his Susanoo to save Sakura from a dangerous enemy. In this scenario, Sasuke, seeing Sakura in peril, quickly activates his Susanoo. The powerful, spectral form of the Susanoo reaches out with its massive hand and grabs Sakura, pulling her to safety. This moment could be a turning point in their relationship, with Sakura realizing anew how much Sasuke still cares for her, despite their past differences.
In such fanfiction, Sakura might be depicted as more alluring and perhaps more bold in her interactions with Madara. Madara could be shown as having a certain charm that draws Sakura to him.
There could be a fanfiction where Sasuke grabs Sakura with Susanoo during a chaotic event like a village - wide attack. The Susanoo's large form is able to cut through the chaos and reach Sakura just in time. Afterward, they have to work together to fend off the attackers. This shared experience could strengthen their relationship and make them more open to each other about their feelings and intentions.