Well, perhaps in this fanfic, Naruto being raised by Mikoto means he has a more stable and loving upbringing. He could be friends with Sasuke from a very young age, and they might grow up like brothers. Naruto would also be exposed to the Uchiha's rich history and culture, which could shape his understanding of the ninja world and his own place in it. He might even get to know some secrets of the Uchiha clan that no one else outside the clan knows.
Naruto's personality could be a lot more family - oriented. Mikoto is all about family, so Naruto would likely pick up on that. He'd be more in tune with the importance of family bonds. Also, he might be less of an outcast as he'd have the support of the Uchiha family, which could make him more confident and less of a prankster.
No, it's probably not popular. A good Naruto fanfic usually has a title that is both appealing and in line with the values of the Naruto community. This title contains a derogatory word which would likely turn off many readers, so it's not likely to gain much popularity.
Naruto could be more empathetic towards the Uchiha's cause. Since Mikoto is his mother figure, he would be exposed to the Uchiha's history and their grievances from a young age. This would make him more understanding of Sasuke's later actions and more likely to try and find a peaceful solution for the Uchiha's problems.
One idea could be that Mikoto discovers baby Naruto alone and decides to take him in and protect him, raising him alongside Sasuke. This could lead to a very different dynamic in the Uchiha clan and Naruto's growth.
One possible plotline could be that Naruto grows up with a different set of values. Mikoto might teach him more about the Uchiha clan's ways, which could influence his fighting style. He may also have a closer relationship with Sasuke from the start as they are both in the same 'family' of sorts.
A 'naruto mikoto lemon fanfic' often has a blend of the Naruto universe's elements with the relationship between Naruto and Mikoto. The fanfic may include the use of jutsus, ninja clans, and the overall world - building of Naruto. Regarding the 'lemon' part, it usually means there will be some level of romantic or sensual undertones, which could be used to develop the emotional connection between the two characters. However, different authors will have different takes on how much and how they portray this aspect.
One idea could be a story about Kushina and Mikoto being friends when they were young and how their friendship influenced Naruto's life. For example, they could have made a pact to always look out for each other's children. Kushina might have told Mikoto some special Uzumaki techniques that Mikoto then passed on to Sasuke in a way. Another idea is a time - travel fanfic where Naruto goes back in time and meets his mother Kushina and Mikoto when they were in their prime. He could learn a lot about the past of the village and his family from them directly.
Since the title seems a bit unorthodox, it's hard to tell precisely. But if we assume it's a regular Naruto fanfic with Mikoto in it, it might explore aspects of Mikoto's character that were not fully explored in the original Naruto series. It could be about her backstory, her relationships with other characters, or her role in some new plotline within the Naruto world.
One main theme is often the relationship between different clans. Since Naruto is from the Uzumaki clan and Mikoto is from the Uchiha clan, the fanfic might explore how these two clans interact through their relationship. For example, in some fanfics, they try to bridge the gap between the two clans that have a history of mistrust.