When I first watched the series, it was only when it was actually said that
Ritsuko was having sex with Gendo that I realised that she was heterosexual.
All throughout the previous eps, she was definately registering a 10 on my
gaydar.

There are so many hints that she is a lesbian. She says a few times that she
thinks that relationships between men and women are illogical, that she is
"the sort of woman who'll never have children of her own" (I thought it was
pretty blatent that she was into women at that point) and she taunts Misato
about being the only one of their group of friends not married by the age of
30, but doesn't include herself in this. She also hates seeing Misato with
Kaji (jealous of him?) and thinks that Shinji living with Misato is sick.

Then there are the stereotypes, which anime is never shy of using. She lives
alone with a houseful of cats, she has short hair and a gruff voice (you can
tell there's testosterone there), she dresses in men's clothes when not at
work and dresses to intimidate men when at work (under her labcoat it looks
like she's in bondage gear). Her jaw is pretty square which gives her a
male-looking face and she has an interest in what a lot of ppl would call
"boy's toys" (you know, computers and electronics and shit). If I didn't
know better, Id say that Ritsuko was a 'lipstick lesbian'.

Does anyone else think that Anno originally intended for Ritsu to be a
lesbian, but changed his mind near the end of the series (there are a lot of
things in Eva that seem to be made up as the story unfolds)? t seems that
her character does a complete 180 in the last 2 eps and she suddenly decides
that she is straight after all.