Probably a mix of all three. She's also probably around the average age range as many contributors and readers. Lots of people have grown up with her and likely have fantasized about doing lewd things to her.
Plus, let us not forget, she was Hermione Granger. Harry Potter is like its own genre in terms of internet fiction.
I might have added "She seems so sweet and innocent, so wouldn't it be fun to corrupt her or see a wild side?" I mean she's no Kim Kardashian or Bella Thorne.
I have a suspicion that on top of what has already been cited (no nudity, early HP crush, sweet and innocent etc.), the politics will have amplified the vaguely taboo appeal. Some may enjoy fantasizing about sexually breaking a feminist icon into submission. That particular aspect ain't my cuppa tea per say, but that's the vibe I get or remember getting from stories involving Emma Watson.
Yes, it seems that, for a multitude of reasons, Emma Watson doing anything near the typical female role in a CHYOA story is wacky and uncharacteristic.
I honestly will have to defer to everybody else on here. Don't see it. Like... at all. I think her character in Harry Potter is a self-righteous, florid, fatuous Fathead, and her online persona ain't much different.
Honestly, just my opinion since I don’t even like celebrity stories anyway. It’s more of a nostalgia value thing like princess peach or zelda, rather than them actually being particularly pretty. I mean, just my own thoughts...she’s fine. Just..fine. Nothing exceptional that really stands out. But the appeal comes from Harry Potter fans who feel connected and closer to it, which is why celebrity stories usually do well to their fanbase. Those people are already fans of the character/person, so of course they are going to praise it. In a games sense, we can all name at least four or five hyped up “Oh, so sexy” characters that we think are absolute garbage but just common because they’re from popular well known franchises rather than being particularly appealing themselves.
I don't like her, like at all. That said, think much of the thing with her is that she essentially grew on screen with the Harry Potter franchise. That has several implications, a few really unwholesome... Can you name something big or important she's done after HP? No googling!
... Beauty and the Beast? The Perks of Being a Wallflower? Little Women? Love her or hate her, Emma Watson has, without any doubt, had far more of a cultural impact than her two co-stars. Daniel Radcliffe might be a contender, but he really only appears in obscure films in which he personally sees potential. Radcliffe essentially just does whatever he wants; Watson is one of the few actors who continually seeks the biggest roles she can get, even after her career's highest point. Again, I'm indifferent toward her myself, but I honestly cannot tell if you're being sarcastic with that question.
I give you Little woman on faith and name, and because I like Greta Gerwig,(I haven't seen it though), but Beauty and the Beast? Come on, just 'cause mama Disney puts her fat coin pocket at use doesn't really qualify a movie as 'big', which means meaningful, impactful, memorable. That's just an easy win for you. Her public personality if far greater than her acting stature, in my opinion. Great actresses are another thing, she's just a name. Edit. To clarify, the whole point of discussing her career was to reinforce my opinion that most of her following comes form fans of the H.P. franchise.