Painter seems like one of those women who was part of Key Club and student government and prom committee in high school. One of those sickeningly nice people who make you wonder what they're getting out of it. The fact that she's a grown woman who seems to primarily be into Harry Potter and Pokemon instead of more sophisticated adult things reminds me a lot of those kinds of women, who are still super into Disney and shit despite being 30+ years old.
So, what I'm saying is, she's friends with the poor autistic tranny because it gives her the warm fuzzies and makes her feel like she's doing God's good work for the lost souls. Being nice to him to feel good about herself.