Naruto might be initially surprised. He's always seen Hanabi as Hinata's little sister. So, he could be caught off - guard by her feelings.
The Hyuga clan members would be very confused by 'Hanabi' (really Naruto). They would notice her (his) un - Hyuga - like behavior and attitude. For example, Naruto's loud and friendly nature would be a stark contrast to Hanabi's more reserved Hyuga self. As for Naruto's friends, they would be puzzled by 'Naruto' (actually Hanabi). They would wonder why he (she) seems a bit different in combat and decision - making.
Well, Hanabi falling in love with Naruto could also lead to some interesting interactions with her sister, Hinata. Since Hinata has her own feelings for Naruto, there could be some sisterly drama. Hanabi might feel guilty about her feelings for Naruto at first, but then realize that she can't control who she falls in love with.
In this fanfiction, Naruto's personality could shift in a few ways. He'd likely become more attuned to the needs of the Hyuga clan, trying to fit in and understand their ways. His impulsiveness might be tempered a bit as he has to consider Hanabi's feelings and the traditions of her family. Hanabi would change too. She'd become more flexible, learning from Naruto's ability to adapt to different situations. Her quiet nature could gain a bit of Naruto's boldness, and she might be more willing to speak up for what she believes in, especially when it comes to their relationship.
Hinata might be a bit surprised at first. Since she also has feelings for Naruto, she could feel a bit of jealousy. But being the kind person she is, she would probably try to be understanding and not let it affect her friendship with Hanabi.
Often, Hinata might be included. Since Hinata has a long - standing relationship with Naruto in the original series, in a harem fanfiction, she could be part of the group. Also, Sakura could be there. She has her own complex relationship with Naruto in the original Naruto story, so it makes sense for her to be in a harem setting with him in fanfiction. Another character could be Ino. She is also a female ninja who has interacted with Naruto and could potentially be part of this harem scenario.
In the fanfiction, a big challenge could be the jealousy or interference from other characters. There might be other people who have feelings for Naruto or Hanabi. For Naruto, Sakura might still have some unresolved feelings, and she could potentially cause some problems for their relationship. For Hanabi, there could be members of the Hyuga clan who oppose her being with Naruto, thinking that he is not a suitable match for her in terms of clan traditions and politics. All these factors combined would create many challenges for Naruto and Hanabi to overcome.
Naruto's character could develop by becoming more protective. After saving Hinata and Hanabi, he might realize how much they mean to him and the village. This could make him more vigilant in looking out for threats against them and the rest of the clan.
Hinata would probably be very shocked at first. Since she has feelings for Naruto as well, she might feel a bit betrayed but also happy for her sister. She would be in a very conflicted state.
It changes his home life completely. Instead of coming back to an empty place, he now has Hinata and Hanabi around. This means more social interaction at home. Naruto has always craved a family, and now he has a piece of that with them. It also affects his daily routine. He might have to be more conscious of his actions, like not being as loud or messy as he used to be. And in terms of his ninja work, Hinata and Hanabi could be a great support. For example, if he's injured on a mission, they could take care of him at home.
His experience in numerous battles has made him more strategic. When it comes to saving Hanabi, he can quickly assess the situation and come up with a plan. For example, if there are multiple enemies, he knows how to divide and conquer. His ability to make quick decisions, which he developed over time, is crucial in getting Hanabi to safety.