It could also be that Dolohov's desire for Hermione causes a rift among the Death Eaters. Some might see it as a distraction or a sign of weakness. This internal conflict within the Death Eaters could then be exploited by Hermione and her allies to their advantage in the fight against the dark side.
One possible plotline could be Hermione getting to know Dolohov in an alternate universe where he has a different side to him. Maybe she discovers some hidden good in him and tries to redeem him.
Well, perhaps he wants to get some information from her. Maybe he thinks Hermione, being so intelligent, knows something valuable about the wizarding world or some secret plans. He could also be trying to manipulate her into doing something for his side in the ongoing magical conflict.
Check out some Harry Potter fanfiction blogs. There are bloggers who curate and recommend fanfictions. They might have come across some 'Dolohov wants Hermione' stories and can share the links with you.
Well, one plot development could be that Hermione is initially shocked but then realizes she has feelings for Fred too. They then have to deal with the reactions of their friends, like Ron being a bit miffed at first. Another could be that Hermione rejects Fred's proposal at first, but as the story progresses, she sees how much he truly loves her and changes her mind.
One popular place to find such fanfiction could be Archive of Our Own (AO3). There are likely many stories there that explore this concept. Just search for 'Dolohov wants Hermione' on the site and you'll get a list of relevant fics.
In a 'hermione meets dolohov fanfiction', perhaps Dolohov is captured by the Order of the Phoenix. Hermione is assigned to interrogate him. At first, they are hostile towards each other. But as they interact more, they start to understand each other's motives a bit better. Dolohov might even start to have second thoughts about his allegiance to the Dark Lord because of Hermione's strong beliefs.
Another development might be the reaction of their friends. Harry and Ron might be initially skeptical or even opposed to this situation. There could be a lot of tension within the group as they try to come to terms with what it means for Hermione to be claimed by Remus. It could also lead to some rifts in their friendships at first.
The plot could involve the mistletoe having some sort of magical effect. Maybe it makes Snape and Hermione relive certain memories. As they do, they start to understand each other better. For instance, they might see how they both overcame difficulties in their pasts, and this new understanding could bring them closer together.
Another possibility is that her growth spurt could lead to some comical situations. Maybe she can't fit into her old robes anymore and has to constantly adjust them during classes, which becomes a running joke among her friends. Also, it could affect her Quidditch skills if she decides to play. A taller Hermione might have an advantage in reaching for the Snitch or blocking opponents.
One possible plot development could be that Sirius becomes a sort of protector for Hermione. He might use his knowledge of the wizarding world and his own skills to keep her safe from various threats. For example, if there are dark wizards after Hermione due to her intelligence or her connection to Harry, Sirius could step in and fend them off.