The original Naruto story has a set of rules regarding the nature of chakra, ninjutsu, and the relationships between different species and entities. In the 'naruto impregnates kyuubi fanfiction', all these rules are thrown out the window. It's a huge deviation as it brings in a concept that is not only inappropriate in the context of the original Naruto story but also changes the fundamental understanding of the characters and their capabilities. For example, the Kyuubi is no longer just a source of power for Naruto but is now involved in a very different kind of relationship that was never even hinted at in the original series.
The original Naruto story is about ninja adventures, friendship, and Naruto's growth. The fanfiction you mentioned involves inappropriate and non - canon sexual themes which have no place in the original Naruto universe. It completely changes the nature of the story and the characters.
Well, obviously the gender change of Naruto is a major deviation. In the original story, Naruto is male and his actions and relationships are based on that. In the fanfiction, as a female, her interactions with characters like Kakashi or Jiraiya could be completely different. Jiraiya, for example, might train her differently considering she is female.
Well, in the original Naruto story, Naruto is mostly seen as a hero or an underdog trying to prove himself. But in this fanfiction, he is feared. This is a huge deviation. The original Naruto is all about friendship, hard work, and believing in oneself. In the fanfiction, it seems to focus more on the negative perception of Naruto, which changes the whole dynamic of his character relationships.
The character dynamics are likely to be very different. In the original, Naruto is seen as an underdog trying to gain recognition. As a monster in the fanfiction, he might be feared or shunned, which is a huge departure from the original story where he gradually earns respect through his hard work and determination.
The original Naruto story doesn't depict Naruto as bipolar. So in this fanfiction, it's a major deviation. His stable and determined character in the original is replaced with a more erratic one.
In the original story, Naruto loves ramen. It's a big part of his character. So in this fanfiction, it's a complete opposite. It changes the fundamental aspect of his relationship with food.
The original Naruto story shows Minato as a hero and a loving father. In fanfiction with abuse, it completely goes against this. It changes the core relationship between Minato and Naruto.
In the original Naruto, the characters are constantly building relationships and working together. But in antisocial fanfiction, Naruto may be shown as rejecting these relationships. He could be written as being bitter and cynical, which is a far cry from the optimistic and determined Naruto we know. This deviation changes the overall feel and message of the story, moving away from the themes of unity and hope that are central to the original.
The obvious deviation is the physical transformation of Naruto into a catgirl. In the original story, Naruto is a male ninja, while in the fanfic, he takes on a more feminine and feline form. This changes his appearance and likely his movement and behavior as well.
The original story promotes values like friendship, hard work and growth. However, in this fanfiction, the idea of Kakashi abusing Naruto goes against those values. It creates a much darker and more negative atmosphere compared to the positive - minded original Naruto story. Naruto's journey in the original is about overcoming obstacles with the help of his friends and mentors, not being abused by them.