Since we are on the topic of Riya, before we go on about hating her, what if there is a reason behind her xenophobia? Maybe it was a traumatic experience:
For example; Maybe she was in high school. She was a sophomore (2nd year if you're English... or I could be wrong) and her freshmen year went pretty well. She made some new friends, even got herself a boyfriend.
Well lo and behold, whatever species your character is, this asshole shows up and just lays into her, saying just the nastiest things. He does this everyday.
Female wise, same thing, just replace he with she.
Herm characters, do as you will.
All the way to her senior year, she has to deal with this asshole, your character's species, tearing her down. Every single day. Now she has no friends, her boyfriend left her because he got a little touchy feely, he's best friends with asshole, and now the school calls her Chicky- Dicky because she has male genitalia.
So after high school, she vowed to never be weak, she vowed to never let anyone try to make her submit. So that is why she can be tough as nails at times.
The reason she hates you is because you look like him. Same species, same smug look, she sees him in you, even if you and asshole aren't related.
Or maybe she's just a bitch. Either way, if you don't like her, ignore her. You don't have to talk to her. It's not like the game makes you speak to her. Just walk on by.