True. And -- as you say -- it is because he has been written as a seducer but it is also due, in part, to the fact that he has the greatest potential for growth as character. In the morning after scene we (literally and figuratively) see how wounded he his and how his life would improve were he freed of his master.
Shadowheart had the same potential but Patch 3 kinda ruined her. She went from being a tough nut to crack, the person who lets very few people past her armor, to someone who gets gushy and cuddly after a night of kissing.
Notice how Shadowheart's meme economy has fallen while Astarian's has risen? Before the SH changes people were making goth-shadowheart / shadowheart disapproves memes. Now that she's gotten so darn agreeable people have turned their attention to the traumatized vampire spawn.
Is that a fair assessment though? Patch 3's disapproval change was for all the characters, which implied that the even the developers felt that the gateway to getting to know the characters was a tad too narrow. It was something even said in their recent interview. Hell, even Patch 4 added reading Astarion's mind, which made me sympathize for him in a scene I had otherwise read him as wholly manipulative before. The patch didn't ruin her.
The Shadowheart Larian wants players to know is more visible to see in Patch 3 than before, and the memes were of a caricature rather than the character itself (as all memes are). When people say the female characters are too mean I always want to correct them and say only Lae'zel is mean (bless her heart). Shadowheart was always intended to have a soft heart beneath it all.
I also think romances are most popular with women, and online fandom participation is more popular with women. So it does not surprise me that Astarion fans eclipse the fans of other characters in fandom spaces. No hate on that since I am part of that demographic. But I wouldn't use that as a metric of which character is the best written since I've seen many of these same fans boot or kill Shadowheart because she overrides Astarion's scenes. Give Astarion a chance by all means, but do the same to the others lol.
Did you know that almost all the phone game with "dating" components are aiming exclusively at straight guys. These dating sims type games tend to be more popular with guys as well. They made billions of dollars on that audience alone. In almost any game, the romance contents tend to be aiming at straight guys just based on the number of options and contents, so I would say it's the opposite. With that being said, the most popular romance is Gale followed by Shadowheart, based on their data. That should give you some indications because Gale's romance is pretty buggy and you could miss it if you don't get all of his approval scenes, and yet his romance is the most popular option based on actual statistic data. You can't judge the number of fans based on online presence. There are cases of passionate fans or "stans" who participate in these discussion more but when the polls or actual data are revealed, these characters fall behind in popularity.
