Yes, there are likely fanfictions out there with this concept. The Naruto fandom is vast and creative, and crossovers or unique concepts like Naruto having White Zangetsu are not unheard of. You can start by searching on popular fanfiction websites.
Perhaps in this fanfiction, Naruto is given White Zangetsu as a gift from a mysterious figure. With it, he discovers new powers and abilities. He might have to train hard to master it, and in the process, he could face challenges not only from his own world but also from forces that are attracted to the power of White Zangetsu. This could lead to new alliances and enemies for Naruto, completely changing the dynamics of the Naruto universe.
One common theme is the battle between good and evil within Ichigo. His normal self represents the good, while Dark Ichigo represents the more primal and sometimes malevolent side. Another theme is self - discovery. As Ichigo grapples with Dark Ichigo, he often discovers new aspects of his own power and personality.
Well, I know a fanfiction named 'Twilight of the Ichigo'. In this story, the author vividly depicts the psychological struggle between Ichigo and Dark Ichigo. It also involves some other characters who are affected by this internal conflict. Another fanfiction is 'Eclipse of the Self'. It shows how Ichigo tries to come to terms with his dark side, which is full of twists and turns.
They might have all kinds of adventures. Ichigo could use his Soul Reaper powers in the magical world of Hogwarts. Maybe he'd face off against dark wizards with his zanpakuto. Dark Ichigo, being more chaotic, might get into trouble with the Hogwarts rules and end up in a duel with some of the more hot - headed students.
Maybe Naruto uses his shadow clone jutsu to surround Ichigo and keep him safe from any approaching threats. The clones can act as a first line of defense, alerting Naruto of any danger.
I'm not sure about a specific 'Ichigo and Orihime lemon fanfiction' title off - hand. But you can often find great ones on fanfiction websites. Just search for 'Ichigo Orihime relationship fanfiction' and look through the results. You might have to sift through a bit to find the ones that are well - written and suit your taste.
There could be Byakuya. He would be shocked and disappointed by female Ichigo's betrayal as he might have seen her as a promising comrade. Also, Rukia. Since she and Ichigo have a special bond, her reaction to Ichigo's betrayal would be very emotional. And then there's Aizen. He could be the one who tempted or manipulated female Ichigo into betraying, seeing her as a useful pawn in his grand schemes.
Ichigo's speed in the manga is hard to quantify exactly. It depends on various factors like his state of mind, the nature of the enemy, and the level of his spiritual power. But one thing's for sure, he's often shown to be very swift when needed.