In a fight over Hermione, neither Sirius nor Remus would truly 'win' in a traditional sense. Hermione is an independent and strong - willed character. She wouldn't just be a prize to be won. If they did fight, it would probably end up with Hermione being angry at both of them for treating her like an object. In the end, the real victory would be for them to respect Hermione's own choices and autonomy rather than trying to 'win' her in a fight.
Their own personal histories could also be a factor. Remus has always been an outsider in some ways because of his werewolf nature, and he might see Hermione as someone who accepts him completely. Sirius, on the other hand, has had a troubled past and Hermione's loyalty and goodness might be very appealing to him. So, they could fight over who 'deserves' her more based on their own self - perceived worth. And also, they might be fighting not just for Hermione but for a sense of normalcy and a future that she represents in their lives.
In such fanfictions, their fight over Hermione can have a significant impact on the magical community within the story too. If Remus and Sirius are important figures, their feud can cause unrest. It might also affect Hermione's standing in the wizarding world. For instance, if the fight becomes public knowledge, she could be seen as a source of trouble or a desirable prize. This would then attract other characters' attention, either to protect her or to use her in the power struggle between Remus and Sirius.
In fanfiction, Sirius and Remus could fight over Hermione because of their different relationships with Harry. Since Hermione is Harry's close friend, Sirius might think that he should have more influence over Hermione to help Harry better, as he is Harry's godfather. On the other hand, Remus, being Harry's former teacher and friend, also feels a sense of responsibility towards Hermione because of her connection to Harry. This clash of responsibilities and their own personal feelings for Hermione can spark a fight.
It's really hard to say. Percy has his incredible powers over water. He can control water in various ways, from creating powerful waves to using it for defense. However, Reyna is an extremely skilled warrior. She has great combat skills and leadership abilities. If the fight takes place in an open area with a water source nearby, Percy might have an advantage. But if it's in a more enclosed space like a Roman arena, Reyna could use her combat skills and knowledge of the terrain to her benefit.
Itachi. He was a highly skilled and intelligent shinobi. His Sharingan abilities were extremely powerful, and he had a lot of combat experience. He also had a strategic mind, which would give him an edge in a fight over Naruto.
Lavender could potentially win. She might seem like a bit of a girly - girl, but she could have some hidden fighting skills. Also, if she catches Hermione off - guard, she could use her speed or a quick spell to overpower Hermione. However, Hermione is usually very vigilant, so this would be a tough scenario for Lavender.
Thalia might be more likely to win. She has years of experience being on her own and fighting monsters before she joined the group. She is also a very tough and determined fighter. Her ability to call upon lightning is a very destructive power. Percy, while powerful, can sometimes be a bit impulsive in his fighting, which Thalia could use to her advantage to outmaneuver him and land a decisive blow.
It's really hard to say for sure. A lot would depend on the circumstances of the fight. If Cardan could use his surroundings to his advantage, or if Jude could surprise him with a new fighting technique, the outcome could be very different. But overall, considering Jude's experience in combat, she has a better chance.
There are likely fanfictions out there with such a plot, but it's not part of the original 'Harry Potter' canon. Fanfiction often explores alternative relationships and scenarios that deviate from the official story. However, this particular concept might be controversial among some fans who prefer to stick to the more traditional character pairings and storylines in the original series.
I think Sakura would win. She's shown time and time again that she can hold her own in a fight. She's trained with Tsunade and has some serious punch - power. Hinata is strong too, but Sakura has more of an aggressive fighting style that would probably overpower Hinata in a direct fight within the context of fanfiction.