Aaaah, Webtoon thumbnails, a mystery I still can't figure out 
I changed my thumbnail multiple times on there. At first it was just a cropped version of my original cover:

...Which, truth to be told, was never actually supposed to be a "cover" to begin with XD it was just an illustration of Adrian I did a couple of years ago. It DID represent a scene that was going to be in the comic, though, so I went with that.
The results were... decent, but at some point I started to suspect that the whole thing was too dark/creepy for the Webtoon audience. So I decided to crop it in a way that wouldn't show the creepy glowing eyes:
Worked pretty well for a few months, but then again, at some point I felt like it stopped attracting new readers. Tried to study the other WT thumbnails a bit to see what could be done. Most WT thumbnails seem to have a focus either on faces or couples. I don't have any couples in my comic yet and I won't have any for a long time, so I decided to go with a face.
This time I picked Jorn, because I felt he was looking good enough to hopefully attract some audience 
...But alas, he's not the actual protagonist of the comic, and I'm afraid most new readers realized that rather quickly, because after a small influx of new followers, people stopped coming XD
Soooo... I decided to go back to Adrian. Again, didn't have a proper "thumbnail", so I decided to go with a panel from my comic:
I wanted something that could: a. show off my style; b. show my main character in all his grumpy glory and c. hopefully give a hint that the story was a mystery (as in "what is he staring at? :O")
Seems to be working decently so far and even got me a spot in the Canvas Top 30 Horror comics just yesterday 
I miiiiight decide to change it again in the future to reflect my recent style changes/add more clarity (a lot of the details get lost in the actual app
) and possibly include some new hints about the story, but for now I'm letting it stay 