For me, it depends on their personality when it comes to manga. Now, for anime, it’s based on personality and the voice they use. If the voice is too shrill I can’t stand them. It’s hard for me to explain the personality part because it just depends on the situation in the anime. Like for instance, I can’t stand Ino from Naruto at certain times. The same goes for Karin but I just hate her in general in Shippuden. There are many other characters that annoy me.
What makes you dislike an anime/manga character right off the bat?