One of the things I like most about Eret is that unlike other enemies, he was one at the beginning so it still counts, is that he never mocked Hiccup in any way.
Alvin called Hiccup “Stoick’s little embarrassment or runt.” Mildew treated him horribly and blaming the dragon problems on him. And Dagur always pokes at Hiccup’s size. Remember “this little runt of a… well you know what you are.” Even Drago said that Stoick must feel same for having Hiccup as a son!
Eret never did anything like that. He showed no signs of underestimating Hiccup, and the only thing he though was ridiculous about him was that he thought he could change his opinion on dragons.
I really hope Eret’s going to be in the third film, though I’m pretty sure he will be. There’s so much they can do with his character!