How come Kaworu is considered one of the main cast of Neon Genesis Evangelion?
I know he's a huge deal in retrospect, and is essentially the straw that breaks Shinji's back, and his relevance to the plot, etc etc, but people seem to view him as a main player on the field, comparing him to characters like Shinji, Gendou, Asuka Misato etc, people who appear consistantly throughout, despite Kaworu only appearing for an episode (right at the end) and essentially a few short sequences in the movie.
This doesn't include the Rebuild series, of course.
Because his episode was really, really good.
Because fangirls. Kawoshin is ridiculously huge in moonland.
Because he's sexy and gay.