If he asks Hinata, she would probably be overjoyed. She has always been in love with Naruto, so her answer would most likely be an immediate 'yes' with tears of happiness in her eyes.
If it's Sakura, she might be really surprised at first. She used to see Naruto more as a friend, but if in the fanfiction their relationship has evolved, she might give it some serious thought and then either accept or decline depending on how she feels about their new - found relationship. It could be a very complex and emotional reaction.
Well, in this fanfiction, Naruto could be nervous as he asks Hinata to marry him. He might fumble with his words a bit at first. But once he gets going, he would talk about their journey together, from being classmates to comrades in battle. Hinata, on the other hand, would be in shock initially, but then her love for Naruto would shine through and she'd accept with tears of happiness in her eyes.
Well, one possible plot could be that after years of fighting side by side and having a deep understanding of each other, Sasuke finally realizes his true feelings for Naruto are more than just friendship. He might plan a very private and special moment to pop the question. Naruto, being the open - hearted person he is, would be initially shocked but then consider it seriously as he also values Sasuke deeply.
For Naruto, it's a big moment of vulnerability. He's putting his heart on the line, so there's a sense of fear of rejection, but also a deep love and determination. Hinata would be feeling a whirlwind of emotions. She'd be flattered, deeply in love, and probably a bit stunned that Naruto is actually asking her to marry him. There would be a lot of blushing and happy tears from her side.
Well, it could be Hinata. In the original series, they have a strong connection, so in a fanfiction, it's quite possible that Naruto would choose her to propose to.
The relationship would evolve from a deep friendship and comradeship to a romantic partnership. They would have to be more open with each other about their feelings. Sasuke might become more protective of Naruto in a different way, not just as a friend in battle but as a future life partner. Naruto would also be more likely to confide in Sasuke about his insecurities and hopes for the future. Their bond would be strengthened further as they face the challenges of being in a relationship in the ninja world, like dealing with the opinions of other ninjas and the political implications of their union.
One reason could be for power. Combining their strengths through marriage could make them an even more formidable force. Maybe Sasuke saw it as a strategic move to protect their village or to face some greater threat that they are not aware of yet.
The other characters' reactions would vary. Hinata could be happy for Naruto, even if it's not her he's proposing to. She has always respected Naruto's choices. Kiba might make some teasing remarks, like joking about how Naruto finally settled on Ino instead of chasing after Sakura all the time. And Choji would likely be supportive, since he's friends with both Ino and Naruto. He might offer to help with the wedding preparations if things go that far.
She would be overjoyed. Given all they've been through, this would be a culmination of their relationship. She'd probably say yes immediately and start thinking about the wedding plans right away.
They could start as friends who gradually realize they have deeper feelings. Maybe they work together on a mission and see each other in a new light. Naruto could notice Ino's intelligence and kindness, and Ino could see Naruto's growth and determination.
One possible plot could be that Harry plans a very elaborate and private proposal. He takes Ginny to their favorite place in Hogwarts, perhaps the Room of Requirement set up as a beautiful garden filled with the flowers Ginny loves. He gets down on one knee and tells her how she has been his rock through all the post - war chaos and how he can't imagine a future without her.