Well, it's sort of popular. Some fans really dig it because it combines two very different elements from the Naruto world. However, it's not as mainstream as some of the more common pairings in the Naruto fandom. The Fem Juubi is a really out - there concept, and when you pair her with Naruto, it creates a whole new dynamic. But not everyone is into this kind of pairing, as some prefer to stick to the pairings that were more hinted at in the original series.
One common theme is power. Since the Juubi is a very powerful entity in the Naruto universe, a Fem Juubi often brings a new perspective on power. For example, how Naruto might have to deal with this new and potentially more complex form of power. Another theme could be redemption. The Fem Juubi might be portrayed as a character seeking redemption, and Naruto could be the one to help her in that journey.
Yes, there might be. There are numerous fanfiction stories out there in the Naruto fandom, and with such an interesting concept as 'naruto is juubi x fem bijuu', it's quite possible that someone has written a story about it. You can check on popular fanfiction websites like FanFiction.net or Archive of Our Own (AO3).
Sure, there are. Some writers focus on the relationship in a more platonic or adventure - based way. For example, they might explore how Naruto and fem Itachi could team up to face a common enemy in the Naruto universe. These types of fanfics usually emphasize the bond between the characters without any inappropriate content.
The female Kyuubi might start with a relationship of distrust towards Naruto. After all, the Kyuubi has a long history of being feared and hunted. But as Naruto shows her kindness and understanding, she could gradually warm up to him. The female Juubi, being a more mysterious and powerful being, might be initially indifferent to Naruto. However, when she sees his determination and the good in him, she starts to respect him. Their relationships would develop through shared battles and experiences, with Naruto constantly proving himself to be a worthy ally and friend.
There are several common themes. Firstly, the theme of transformation. Both Naruto and the Fem Juubi may change and grow as a result of their relationship. Naruto might become more understanding of the greater powers in the world, and the Fem Juubi could become more in touch with her human side. Secondly, the theme of sacrifice. They may have to sacrifice certain things for the sake of their relationship, like Naruto sacrificing some of his time with his friends to be with the Fem Juubi. And finally, the theme of unity, as they combine their strengths and weaknesses to form a stronger bond.
There might be fanfics with the 'fem naruto' concept, but the 'big futa lemon' part sounds like it could involve inappropriate content. Naruto fanfics usually focus on aspects like character development, alternative storylines, or relationships within the Naruto universe that are more in line with the general spirit of the series. So, I wouldn't recommend seeking out something with that kind of title.
One plot idea could be that the Fem Juubi, in a more sentient form, initially sees Naruto as a threat due to his power. But as they interact, she discovers his kind heart. Maybe Naruto has to convince her to use her power for good instead of destruction. For example, he shows her the beauty of the ninja world and the bonds between people.
Yes, there are many. You can start by looking on fanfiction websites like FanFiction.net or Archive of Our Own. Just use the search terms 'Naruto and Fem Juubi' and then filter the results by rating to avoid any adult - themed stories. Some fanfictions might focus on their unique interactions, like how a Fem Juubi could change the Naruto universe's power dynamics.