I'm trying to find an American (?) cartoon series, all I remember is that it's about two kids (brothers or maybe even twins). One of them is nice, and another is evil, he's always scheming and pulling pranks, and planning to kill the nice brother (I think). And he's blue for some reason. )))
No mutants, no aliens, no superheroes, etc., just a story about that family.
Um.. that's all. Does it sound familiar?