Most likely not. Fanfics with such themes are often inappropriate and violate the general ethics and norms of the Naruto series. The Naruto series is mainly about friendship, growth, and ninja adventures, not such improper content.
The relationship could start as a friendship. They might be comrades who train together often. As they train, they learn about each other's dreams and fears. One day, during a particularly difficult training session, Naruko gets injured and Itachi takes care of her. This event deepens their bond. Later, through some unforeseen circumstances, Naruko becomes pregnant. They then have to face this new situation together, with their relationship evolving from friendship to a more committed partnership as they support each other through the pregnancy.
It could be that Karuma and Naruko are part of a prophecy where their child is meant to be something special. The pregnancy then sets off a chain of events. They have to figure out how to prepare for the arrival of the child while also dealing with political or social unrest in their fictional realm. Their love for each other and their hope for the future of their child drive them to make difficult decisions and overcome numerous obstacles.
I'm not entirely sure specifically as it could vary greatly. 'Naruko' might be a character in some fan - created universe. 'Pregnant' could be a plot point where the character is expecting a child, and 'lemon' in fanfiction often refers to stories with some level of romantic or sexual undertones, but it's hard to say precisely without reading it.
There are some out there. You can start by looking on popular fanfiction websites like FanFiction.net or Archive of Our Own. However, the quality can vary greatly. Some might focus more on the relationship development leading to the pregnancy, while others could be more about the challenges they face during this situation.
Since I don't have access to the 'naruko gets double lemon fanfiction', I can only guess. It might be that Naruko is put into two unexpected or complex scenarios within the story, and the 'lemon' could be used metaphorically to represent something that adds an element of difficulty or uniqueness to the plot. It could also be related to some kind of emotional turmoil or adventure that Naruko goes through, with the 'double' indicating two different aspects of this turmoil or adventure.
A better fanfic idea could be about Naruko and her training journey to become a powerful ninja. For example, she could go on a special mission with her friends to explore a new and dangerous land, and during this journey, they face various challenges and learn new jutsus.
Perhaps in the fanfiction, Itachi and Naruko are on a dangerous mission together. They get trapped in a strange place for a long time. During this time, they rely on each other for survival and their bond deepens. Eventually, Naruko becomes pregnant. But Itachi is worried about his past and the potential danger his enemies could pose to Naruko and their unborn child. So, he tries to find a way to protect them while also coming to terms with his new role as a future father.
The main characters are obviously Naruto and Naruko. Naruto is a well - known ninja in the Naruto universe, famous for his determination and his powerful jutsu. Naruko would be an alternate version of Naruto, perhaps with some different characteristics while still sharing some of his core traits. In the context of the pregnant fanfiction, they are the expectant parents, and the story would likely revolve around their experiences, emotions, and the changes in their relationship due to the pregnancy.
You can start by looking on fanfiction websites such as FanFiction.net or Archive of Our Own (AO3). These platforms have a large collection of Naruto - related fanfictions, and you can use their search functions to specifically look for stories with pregnant Naruko.