I was going to say I didn't have an answer here, because I tend to just like the characters everyone likes, or divisive characters, or I prefer the antagonists (but that tends not to be a unique preference), but then I remembered that I was in both Teen Wolf and Sleepy Hollow fandoms for a brief moment, and my experience of liking wildly unpopular characters caused me to a) back away slowly from both fandoms and b) ultimately leave Tumblr without many regrets.

Regarding Teen Wolf, my favourite character was Scott, and I liked his dopey teen romance with Allison, which was definitely not a popular choice. (I also had zero interest in the fandom juggernaut, either as a pairing or as individual characters.) I remember there was a fairly big meta aggregator comm on Dreamwidth at the time, and all the Teen Wolf posts were long-winded rants about how awful Scott was and how he shouldn't have been the protagonist of the show and so on. (I did only watch the first three series and bowed out because it got too stupid even for me.)

Regarding Sleepy Hollow, I am that one person who actually liked Katrina, at least in the first season (or I suppose I saw the potential in the character, and saw the writers squander it, as they squandered almost everything the show had going for it). I liked the two leads a lot as well, though! I shipped Ichabod/Abbie/Katrina! The whole thing was wildly unfun.

Looking back, those two fandoms (plus Inception) were probably solely responsible for why I completely lost interest in being involved in megafandoms (or even just big-by-Tumblr-standards fandoms like Sleepy Hollow). It was so lonely and unpleasant to like characters and ships that everyone else hated. (I mean obviously this is a really tiny problem in the scheme of things and I am very happy doing fandom the way I do it now, but your prompt caused me to look back and see connections between a lot of things that I hadn't really joined the dots between until now.)