Who is Trish from Geography Club and what is their importance?

Trish is a small and mousy girl that has a crush on Russel. When Gunnar double dates with Kimberly, Trish is the girl that goes out with Russel. Trish kisses Russel and tries to get him to have sex with her a couple of times. When Russel refuses to have sex with Trish, she and Kimberly starts rumors that Russel is gay.