Why do some readers/writers dislike an ambitious, talented and compassionate female character like Hermione but love charachters like Lavender or Myrtle whos shown to be average and desperate for attention from boys?
So there are a couple of things going on here.
One is that people don't like perfect characters. We have names for perfect characters - like "goody-two shoes" and "mary sue."
I love Hermione to bits, but I love that while she's good at observing people, she's actually not great at people. She can miss things, accidentally be judgy or insulting, accidentally come off as too intense and annoying. Of course, sometimes she's intense and annoying on purpose, and that ties into her "bring a gun to a knife fight" problem solving strategy. I love that she has a tendency to panic and freeze up, I love that she argues for fun, that "pleased" on her often manifests as "smug." I love that she's a workaholic, and has this intense need to be useful that leads to her downplaying or hiding her own issues - and playing a kind of support-staff mom-friend role that she does chafe against if she does it too long.
But. I also get that Hermione reminds a lot of people of that cousin who picks fights about politics at Christmas. If someone finds her annoying and self-righteous in a way that isn't compelling, I get that.
I do think there's one more thing going on here, especially with this particular collection of characters. Recently, I've been watching a push back against JKR's framing, which I'm honestly enjoying very much.
Basically, there are some characters who get really flattering edits in the books. Hermione, Mrs. Weasley, Dumbledore are good examples of this. The narrative voice works hard to justify, excuse, or downplay everything they do that's shady, mean, or unpleasant. (and they all do shady, mean, and unpleasant things.)
Then there are characters who are given really unflattering edits. The narrative punishes them, goes with worst possible interpretation of their actions, likes embarrassing them or painting them as pathetic or silly. Draco is the poster boy for all of this. Rita Skeeter is another great example. And I'd say Myrtle and Lavender get pretty negative framing as well.
And so, I think there's a tendency in the fandom to try and flip that framing. Fanworks, and especially fanfiction, want to supply something that wasn't there in the original. The books (and the Fantastic Beasts films especially) are full of unquestionably good, god-like Dumbledore. So what if we explored his darker, more manipulative, side? Hermione's getting hit with some of that as well, and I don't think it's surprising. I think this might have something to do with the slow fandom swing away from Remus... although he's a less clean example, since he was framed very negatively during the later books.
And then of course, the flip of this exists too. Draco obviously, but I'm seeing a real interest in reframing and fleshing out the HP characters who were not treated well by the narrative, especially the ladies. Instead of treating them as stock characters and villains, lets give them the benefit of the doubt. What does it look like inside their heads? Are they really as bad as the narrative makes them out to be? Bellatrix was probably the first, because she's sort of a goth Harley Quinn and has a great look. But now I'm seeing a lot of love for like - Rita Skeeter, Parvati, PANSY. People are shipping Umbridge now apparently?
So Myrtle. Treated a comic character, but once you take away thaat framing she's tragic. (and one of Voldemort's first victims, which gives her a very interesting place in the narrative.) If anyone knows a good fic covering the period in Book 6 where Myrtle and Draco were besties, link me. That has the potential to be such a interesting relationship. Myrtle is of course a perv, which is bad, but also fits in with the way that the books don't take sexual misconduct seriously when it's girl-on-guy. I'd love to read something that leans into those tendencies of hers. Make her a proper, scary villain. Maybe she and Tom Riddle had a past. Myrtlemort lets gooooo.
And... Lavender is in the running for the single character treated worst by the narrative. She didn't do anything, she's just kind of there. She seems girly and femme. She likes Divination. She has a pet rabbit who dies. She's into Ron. She joins the DA, she's part of Neville's resistance. And then the "Won-Won" segments frame her as the most embarrassing, desperate, cringy person who has ever existed. and then she's attacked by Greyback? and in film canon dies? What a thankless character arc. I'm not surprised at all that people have taken that and had fun with it.
Also, just putting this out there. Hepizbah Smith. You guys. Show me Hepzibah Smith with some different framing over the top. She's low-key Tom Riddle's sugar mommy, that is so interesting. Aunt Muriel, she should be a staple of Young!Dumbledore fics. She is mean, and wears crazy hats, and reads people for filth, and has all the tea on everyone. (Also is there a Mr. Aunt Muriel? no there is not.)
Okay. okay. one last one and then I'll stop.
Griselda Marchbanks. Very minor character obviously, BUT. She's high ranking Wizangamot, quits in solidarity when Dumbledore loses his seat, runs the OWLs/NEWTS, and Lucius Malfoy and Augusta Longbottom are in a friendship tug of war over her. I have to know more.